0. Notes for Engineering Mathematics A ... ;.~\- \;:;?\ '\SJ ~;; :\ }.·\ . . ··~· . ·.. ..: .. ,, . ' ' ... Acknowledgements Project Manager: Max Gregory Writers: Jon Phillips Mel Williams ~ ijiJ Section 1 Arithmetic 1.1 1.2 1.3 (' ·: Rational numbers and surds S.I. units and scientific/ engineering notation Approximations, errors and significant digits Review Answers to activities ta Section 2 Algebra 2.1 2.2 2.3 2.4 25 Basic Algebra Indices and linear equations Factors and simple trinomials Factors of harder terms Transposition and evaluation Review ...j Answers to activities Section 3 Geometry 3.1 3.2 3.3 3.4 Angles Triangles Quadrilaterals Trigonometry Review Answers to activities Section 4 Coordinate Geometry 4.1 The number plane 4.4 The equation of a straight line 4.3 4.4 D . '\ Function notation Simultaneous equations Review Answers to activities Section Contents .~'.: - 1.1 1.11 1.12 1.13 1.14 1.2 124 1.25 1.26 ( . (jllJ Rational & Irrational Numbers Surds Manipulation of Surds Activity 1 S.I. Units and scientific/engineering notation 1.21 1.22 1.23 ,;' 3 Rational Numbers and Surds 6 Indices Base 10 Scientific and engineering notation Activity 2 S.I. units & basic conversions Harder conversions Activity 3 4 ; r::- 1.3 Approximations, errors· and significant digits 1.31 1.32 1.33 1.34. 13 Approximations Errors in measurement Significant figures Activity 4 Review 17 Answers 18 1- 1 . . Arithmetic A \(!:) At the completion of this section you should be able to: f -:..- -:: D simplify expressions involving square roots and cube roots of rational numbers D evaluate expressions involving square roots and tube roots D convert numbers using laws of indices in base 10 D convert values between decimal notation, scientific notation and engineering notation D convert units pf physical quantities expressed in SI units D show awareness of errors in measurement and calculate maximum probable error of a measurement D give results in appropriate number of significant digits D use estimation and approximations to check the reasonableness of results : ,>, t .. €). Cc). (). I 1-2 Arithmetic 1.11 Definition Any number that can be expressed in the form a , where a and b are b integers and b:;t: 0, is said to be rational. For example, the numbers ·na1. -128 - - are ratio 4'5'25 Any number that cannot be expressed in the form a , ·is said to be . b irrational Examples of irrational numbers include tr (the ratio of the diameter of a circle to its circumference), }i, V4. ..fi, 1.12 Surds .J4 = 2 is a rational number since 2 can be written as 21 . Consider the term ./3 (..[j = 1. 7320508... ), which cannot be expressed in Note. that !: . This term is irrational and is called a surd. Any number the form b written -with a radical (.[) si~ that is also irrational, is called a surd. Other examples include: .Js, 3..fi, 1 + ../2, ..ff - .Js. Example 1: Determine ~hether tl:le following numbers are ratio~ pr . irrational. _·. ... . . . .• •. . ... . 9 ' . (a). 0.9 (b) ·. Vf6·· (c) Js (d) 1 <i . -10 . .. ... ........ . . · O9- · · rationalii · . · .Jl6 = 4 rational ... ../5 = 2.236 ... irrational •-· .. Ji (e). ;{ii. (f) Vs . 1 ../3 - 1 ---irrational 1.732.~ .. V27 = 3 ratio~ . (note 3j(3x!3=27) VS =2· · ·. r~ti~nctl . .: ·• •· ·(note 2x2x2=8) ·. 1-3 Apthmeµc 1.13 Manipulating Surds There are some basic rules that must followed when working with surds: ..jab = .Ja Jb X Ji= 7,, c:· '. ® :: ' -: j :•:.· .. : ·.:.·: ...::::\:\.·'.'···:·.···· . ;... ::·:~: :-·, ;'" .. (e):J:ii~f ~i · · ·..·. ·.· . . .r. •. ~.. .:..:... ·. :" . :..-··. ~; ·.::.·:·· . . . . . -: ·..... :...: ::_~·:·· ·.-i:. _:~}'.: ::·/:::{:.;-: ~.. :. . ; ··.•:·:·.. ~ ;/8:ti :: :....Jili.: ..· ·... · · :==Jix~•. ·.·.=3 ,' t~1~!l ·. · ·. 0 . ·. =2 Pih ~ 1-4 · Arithmetic .... 1.14 Activity 1 Use a calculator to evaluate the following (to two decimal places) {a) ../63-../5.i (b) (c) 345 0.123x0.0412 (d} (e) ('.;.. .. ' Vw ../Io-.fi (f) 2.99 + ~./7 .63 3.14 X .Js.g 30-J3o 3 V-1s + s.Jii Simplify the following, leaving your answer as a surd where applicable. ' (b) 2,.J6 X '3-,J5 (c) ../s 8/i. - (d) .Jio +Ji. (e) 10./3 + 5./3 (f) 16./8 + .Js X Simplify, leaving your answer as a surd where applicable. · .,fil (b) 4/& (c) .fii-..fi (d) Flo X Jg "./4o {a) (.. ... ~ ' (e) ® 3l 49 {f) ,4 16 2../6 X 3./5 ~ 1-5 A1 \;_:) .. ···-~·-··.·:-s:.···\~:: --:·: i-'- :.: . · .. . •.... :- ·: ·-~-- . ~: :_ ·= :-:· ....; ·.,·:· - ::·· ... . ..... ~ ;- : .-.:.=-= ··-: • . •. ··:::.:-:::·_;:}?( .~:rr.f,.:i:·::: .·.-:-:·.... 1.21 Indices: base 10 Numbers such as 10, 100, 1000 or 1, 0.1, 0.01 etc, can be expressed in index form by noting the following relationship: 10 1 = 10 10 2 = 100 3 10 = 1000 10n 1 followed by one zero. 1 followed by two zeros. 1 followed by three zeros. =10000 ..... 1 followed by n zeros. We could state further that 10° = 1 10-1 = 0.1 10-2 = 0.01 10-3 = 0.001 1 followed by no zeros. 1 preceded by one zero. 1 preceded by two zeros. 1 preceded by three zeros. ~ ~ When multiplying or dividing numbers expressed with indices some basic rules apply. Rulel 10a x }Ob = 1oa+b Rule 2 IO a + IOb = 10a-b >{c}IO~/:?<:'fO.:; i~:;ilo~i · ·. ·. ::)~~:::t'::;;(:;;i;~ifr~ 2~: ' ·. ' > .. ·• . :-:·.:-. . . =:0.01 .· iii'. J;1&:);{1 o:: ·. • . . • 1 (~) .. , 10 , ~ 10 .· .. ·.;:,,... ·;·;·:·; JO . L:lrli V . A Arithmetic 1.22 Scientific and Engineering Notation 'tt;I 1. Scientific Notation Scientific notation (sometimes called standard form) requires numbers to be expressed in the form a x 1on where I 5 a < l O. ( a must be bigger than or equal to 1, but less than 10). . . ?(ci} 446- = 4l46 x010 l·· : V 2 : .•- The decimal point is placed, generally between the first two digits, to create a number between 1 and 10, and adjustments made to the index of 10. Compare the index with the number of places the decimal point has moved. ·_- Examples:~:fuefcillo~ginscte.rt¥c.:rtotation. · • ::., ·<:·· -~ .. . .. ·.: ... : .::;~::,:-:;.:,:··.-:..~:·· .. ~ Jd) 0~046 ~k6xHf 2 _.- ••. - •• _ ·: : : . . .: ··. . : . : ::._. ··kfo.oo&~ .~ 8~9 x~~~j: · · In the examples: large numbers have positive indices, small numbers have negative indices. 2. Engineering Notation Engineering notation also requires numbers to be written in the form ax ion, but where 15 a <1000 and the index of 10 is a multiple of three 3 3 6 (10- ' 10°' 10 ' 10 etc). Bxa.mple6: Write the following in engineering.notation.. _ (a) 446000 ~ 446x 103 · (c) 12500 = 12.5 X 103 ·-··). -·-··-..-· .... .: .: ·• .•. -_· ·. -_- . (b) 1138,6 :.~. -.. .•· · {d) 72~0000000 = 720; ~0 9 __ . . . '3. _- . {e) 0~046..= 46.0xlO- · ·- (f}0.386 ~386.0 x16~~ .. ;.:.:. . {g):~~000000890 ·= 890 x 10- 9 ®.. = l.1386x 103 . • .. . ~--·· ·. . ... · .. (h) -0~00072~ = 721 x10~.• 1-7 Arithmepc 1.23 Activity 2 . . CB• I 1 Use the index laws to simplify, leaving answers in index form. 10 4 (b) 10 4 + 10-2 10-S X 10 3 (c) 104 10-2 (d) 10-3 X 10-6 10-3 X 10-s (e) 10-2 X 10-4 . 10-S X 10 7 (/) 10-2 + 103 (a) 10 6 X 2 Complete the table below Decimal notation Scientific notation Engineering notation 24700 84000000 0.00123 ,... i6 X 10-l 155 X 10 6 3.52 X 10 5 32.1 X 10-3 3 Write the following as decimals r·· '· (a) 1.35 X 10-2 (b) 75.9 X 10-6 (c) 354.5 X 10 3 (d) 1.345 X 10 4 ~. V /!Pit-. ~ 1-8 Arithmetic ft 1.24 S. I. Units ~ The number system based on multiples of 10 is called the System Internationale or SI system of counting. All units in this system differ by 3 factors of 10 and, in particular, by factors of 1000 or 10 • For example, 1 kilometre is equivalent to 1 x 10 3 metres or 1000m. Each quantity in the system has a base unit The table below lists some of the more common quantities used in engineering, with the appropriate base unit Quantity /, .. -.: ~ lensrth time mass velocity acceleration area volume potential difference current resistance force power work Base unit metres seconds kilograms metres per second _ metres per second squared square metres cubic metres volts amperes ohms newton watt joules Units m s kg ml s or ms-1 ml s 2 or ms-2 m2 m3 V ... A n N w J There are many other units used to express quantities, each one differing by 1000 from the previous one. Quantity pico nano micro milli base unit kilo mega giga Order base unitx 10-12 base unit X 10-9 base unit x IO~ base unit X 10-3 base unit x 10° base unit x 10 3 base unit x 10 6 base unit X }0 9 Prefix p T/ µ m quantity k M G t.:t'".\ 0 1-9 . Arithmetic ... One quantity that is not included. on page 9, but which is commonly used, is centi (base unit x 10-2 ), as in centimetre (cm). Strictly speaking only multiples of 1000 should be used in the SI system. 1.25 Harder Conversions 1 Areas and Volume Consider fue two squares below. They are the same size but each is measured in different units. 1m 1000 mm D1m Area= Im D10d0mm Area 2 = 1000 x 1000 mm 2 = 10 6 mm 2 Both of the squares above are exactly the same. The relationship between units when squaring (area) or cubing (volume) can be shown as: Area lm 2 = 10 6 mm 2 Volume :·Example 8: "Nofofhe 1m 3 followfu.Kconvemons..,.·. · · •· · · . .:::.: :../:· ·(-.:f: :.. :.. ·>- . .--~~::.:··; /·:::: .· ·: .<{·:-.~·.:::_.:.:,_:.-.::~ .·· . :: .·.. ::: ··:·.(g}1·~~; = 109 mm 3 .+.:~kjiQ~:ni2··•.·· . ~-:· ··~::·:· :. :·: ..... ~-..: ... ;.:·:·.<>/:. > . .. =:::·:..t.::::·:.; <:-.:~~· ..... :.. -~ ·,_ ~ ~ ..... :•. ,..,:: ... ;·:·.···;- .. :;: :·.·:.>:_ .... ;·:\•(iIJJ.:mf;;g;··:f.~[ijf-'.f&n-,•:•; . .. 1-10 -.~··: ·. •. ··. \;:. ~-;,.:. :.··,.· @ ... Arithmetic 2 Related Rates Velocity is measured in base units as metres/ second, acceleration as metres/ second squared. These are examples of related rates and when converting units, both quantities must be changed. JL .. ;~ 3 Liquid Measure The litre ( Z), used to describe fluid capacity, relates to volume in the following manner: IZ = 1ooom1 1m1 = 10-3 z 4 lm 3 = 100oz IZ = 10-3 m 3 1ml = 1000mm 3 if(_. ~- - 1 mm 3 = 10-3 ml Example 10: .Convert the following~ ·. · •· .(d}i~j~.~~ i. . . . 3 : . . . .. ~ . . . . ..-.. . .. 3 .· (b)0~58m tp{ :·: 1-11 ..·. '-······~'··:;; Alj.thmetjc 1.26 Activity 3 1 Convert the following = = = (a)2.8km (e)l0 6 g '··· s mm = ms µm = 17s = = V mV GV = A = µA = .MA (d}300kV = (f)3mA (&). Convert the following (a)0.27m 2 = km.2 mm2 ~-= (c) 250 m 3 = cm2 = = mm 3 (e) 30km/h ( cm3 l = . 1-12 (b)53.lµs = kg mg Mg = = = (:i 3 m = n = kn = an (c)6.MQ 2 G) = = = m/s mm/s mm/min (b)4 X 10 6 mm 2 = (d) 12 X 10 6 ml m2 = km2 = cm2 = =. l = mm3 m3 (/) sooz I day = m 3 /h = = ml/s ml/day Express (a) 204g in kg (b) 0.74A in mA {c) 0.94N in kN (d) 12km2 in m 2 (e) 3000ml in mm3 (f) 4 x 10 6 Ml/ day in m 3 / s () ' ... Arithmetic 1.31 Approximations · When working with a calculator to derive answers to any mathematical problem, it is important to have an approximate idea of what the answer should be. This approximation is not meant to be accurate, but is designed to stop wildly inaccurate calculations from giving false results . .:~~~~1~:,1.-~:~i>~f9~tfo!15~the~y()~~:·~!1aticins;>•-· ._.· •t1rz,:1tht1ji40,:tc: ~~~~r¥:i1:::j;t_·titt,jr\2 ·:.:: ..::=t:\:);:\\i. . ·-·:.::.::. !;!!~:~:;~;:; >IF;6•:•.•• ·+-0.5. ?i·"t;t~r~r;_[_ii:" ·'.• ..::: .·:_:··:':";--:·i :::.· : The answers above are not accurate. They reflect the order of the correct answer. If a calculator produced an answer of 23267 for example lO(a), then the approximation allows you to doubt the result-and check the calculations. Also note the use of the ~ symbol to indicate "approximately equal to". 1.32 Errors in Measurement Any quantity measured has a certain error in the measurement. This error may occur for any number of reasons, including: inappropriate measuring instrument; temperature changes; human fallibility. Maximum Possible Error (MPE) When stating an answer for any measurement, the number of decimal places used is often an indicator of the level of perceived accuracy. The Jv.lPE is derived from this accuracy. As an example: a distance measured as 10.3m indicates accuracy to one decimal place or O.lm. The actual distance is between 10.25 and 10.35m and the 1v.lPE =0.05 (one half of O.lm above or below 10.3m). 1-13 Arithmetic ... ' a rustance measured as 10.30m indicates accuracy to two decimal places (O.Olm). The actual distance is between 10295 and 10.305m and the :MPE=0.005 (one half of 0.01 above or below 10.30m). The :MPE could be found by taking one half of the next decimal place in the answer and indicates the range of the answer. The :MPE can a1so be expressed as a percentage of the original measurement. .. . . •..• ::: :;:;: ... •,•.'.,::·; .., ·. ···:,....:~-.;:?:·.~:/:)::··:.:::; ........ ·. :-·-···.: ..... . .. .::: ·:::::·. · : ·:·: ~:·.:. :. : : : : ~: :· . .:-~~-·- ::}~<:::::}::~:.:? '•. ·.. ·:; :;_ ·:;-..::j::::: :/:/>·~=_:\· .: ~~ ·: · : :_._. : ·. 5' ·::.· : =-·:~:..,:.:; :. . ·.·. _;:.·: ;::·:·: ·-··:<:=~=-· ..;;_::.::::·:·\::;.-:::·· .··=:-•--.>X-. ·• ... 6005:•··· •./.a:: : ~-0.00833% . Percentage Error An error of SmA in a reading of 40mA suggests an actual reading somewhere between 35mA and 45m.A. The absolute error is SmA. An error of SmA in a reading of 40A also gives an absolute error of Sm.A. Obviously there is a difference in the accuracy of the two measurements and this can be found by converting the errors to a percentage. C.,. 'Example 12: Convert to a percentage erro! .. · . . .· .. :·.:·:::·:! . ::-: ... ... :·. -~: . .......... •.; ··:·(af1?.~r.:¥:··•·~•n:0-_iit40Trl4.:·i.:: 5 100 .. . ··.•,·'<• .......... =40X.T''' . :~ ...·.!. 1-14 01 \..;F ... Arithmetic 1.33 Significant Figures The accuracy of an answer can also be expressed in significant figures. ForexampIB, _ a measure of 10.3m is stated to 3 sig. fig. and suggests an actual measure between 10.25 and 10.35. a measure of 10.30m is stated to 4 sig. fig. and suggests an actual measure between 10295 and 10.305. There are some basic rules that must be obeyed when working with significant figures. These are: The first significant figure is the first non-zero digit, moving from left to right. All non -zero digits are significant Zeros between other digits are significant. Zeros written after a decimal place are significant. Zeros at the start of a number are not significant. Zeros at the end of a whole number may be significant. If they are some indication should be included with the number. :•••·Number .··1206 ... :0.3010 •, ... i:210 ··· .. 0.301 ·. <> .i•~~'030. ... :.-: .. :... fa·:-: :·: .; :. :.~.· ······ ·-:-:-...·.:·: <;.... .:}t··.:;·:-:·:·:: . > >iiooo:);/·::<:j-): . •. : .::it(3_• . . :··3a4 1.81 . . . . 4 . 4 .. : • •: . ,: E4lx10 . L.405xl0 •..·. 0.00003450 · R0000345 ·.: ,6800. ./:68QO. 3~14159 .... ·:•·. / . . . .· ·: 1.805 In generaL when calculating any practical measurement, cµ15Wers should be given to the least number of significant figures in the information. In practical terms, to minimise error, measurements are written accurate to the least number of significant figures in the data. For example, 98.61 x 51.3 x 0.46 = 2300. The answer is stated to two sig. figures (the data has scores of 4, 3 and 2 sig. figures). 1-15 Review questions These questions will help you revise what you have learnt in Section 1. 1. Name the two measuring systems commonly used in Australia. ·----------------------------·----------------------------- 2. ------- 3. Match the symbols to the units by writing the symbol in the brackets beside the unit. millimetre ( ) in metre ( ) mm kilometre ( ) ft inch ( ) t foot ( ) g yard ( ) op Celsius ( ) yd Fahrenheit ( ) lb gram ( ) t kilogram ( ) km tonne ( ) kg ounce ( ) oc pound ( ) oz ton ( ) m - - - - - - --···- Use a calculator to convert 3.750" into mm. EPC87 Introduction - Measurement Student Workbook January 1999 .......... ~, .... O : O U C A ' T I - ~ 19 il1~1 12. Use a calculator to convert 127 .6 lb into kilograms. 1~. Use the Kilograms, Pounds Equivalents chart to find the equivalent kilograms for 57 pounds. 14. Use the Kilograms, Pounds Equivalents chart to find the equivalent pounds for 98 kilograms. 15. Comparative measurement uses a master component as a standard to compare other components against. True or false? (Circle the right answer) 16. Dirty measuring instruments won't affect the accuracy of measurements taken. True or False? (Circle the right answer) EPC87 Introduction - Measurement Student Workbook January 1999 Ii,,~ . ···--··-a :::::;.: ,.,.o ..""'"""•,;t: 21 '•\ ,• =I . Arithmetic ... 1.34 Activity 4 1 Find approximations to the following and then use a calculator to·find an accurate answer to three sig. figures. (a) 9.8 X 19.5 X 11.8 (b) 199x48+5.l 20.2 X 10.3 X 9.8 5.4 X 14.8 (d) ~51.4 + ../fo34 ~19.2-(13) 3 (c) .Jl03.4 X 3.4 10.6 X .J321 (e} 8.87 X 10 3 + ../38.5 X 10 4 (f) 1.405 X 103 - 23.4 X }06 .Js.32 x 101 2 Find the percentage :MPE of the following. State also the range of each measurement (. ,; :: (a) 6.38m (b) 6.380m (c) 6m (d) 0.006km ,.. (e) 6.38 X 106 µm (/) 638mm 3 Find the percentage error of the following. (a) 4mA in 50mA (b) 0.5V in lkV (c) 2mH in 25H (d) Imm in 15m (e) 120µ.A in 4mA (f) 6Hz in 200MHz 4 Copy and complete the table of significant figures Sionifirant Figures Number 3 2 1 30200m 1.004.A 7.015N 0.003251m 0.03456kg 43000 1-16 \ ¥thme1:ic Answers Activityl 1 (a) 029 2 (a) J6 3 (a) if2 ® (b) 5.75 (b) (b)3 Activity2 (a) 1010 1 2 (:.. fr/3o (b) 106 (c) (d) ~ MO (d) 5.fi. (c) 5../i (c) 10....s (d) 10 7 (e) 526 (f) 11.97 (e) 2 (f) 16 (e) 9.fi. (f) 6,./2 7 (e) 10-2 {f) 107 24700 2.47x 10 4 84000000 8.4 x 10 7 1.23 X 10-3 7.6 X 10-l 24.7 X 10 3 84 X 10 6 1.23 X 10-3 760x 10-3 1.55 X 10 8 155 X 10 6 · 3.52 X 10 5 3.21 X 10-2 352x 103 32.1 X 10-3 0.00123 0.76 155000000 352000 ~.0.0321 3 (c) 68079.56 (d) 0.38 (b) 0.0000759 (a) 0.0135 (c)_ 354500 - (d) 13450 Activity 3 1 2.8 X 10 3 53.1 X 10-6 (a) 2.8 X 10 6 {b) 53.1 X 10-3 2.8 X 10 9 ~.· 53.1 X 10 3 0 X 10 6 (c) 6 X 10 3 6 X 10-3 @ {~\ . 300 X 10 3 (d) 300 X 10 6 10 3 3 X 10-3 (e) 10 9 (f) 3 X 10 3 300 X 10-6 1 3 X 10-9 0.27x10-6 4 250xl0 9 2 (b) 4 X 10-6 (c) 250x10 6 2.7x 10 3 40 X 10 3 250xl0 3 12 X 10 3 8.3 0.02 (a) 0-27x10 6 (e) 8.3xl0 3 (d) 12 12 X 10 9 3 1-18 (a) 0204 (b) 740 500xl0 3 (c) 0.00094 (f) 5.79 500xl0 3 (d) 12 X 10 6 (e) 3 X 10 6 {!) 462% e Arithmetic .... A u Activity4 1 (a) 282 2 (b) 0.919 (c) 0.182 (5.5-6.5) (e) 0.078 % (6.375-6.385) 3 . (f) 594 (b) 7.84x 10-3 % (6.3795-6.3805) (a) 0.078% (6.375-6.385) (c) 8.3 % (e) 9490 (d) 1.79 X 10 6 (d) 8.3 % (0.0055-0.0065) (f) 0.078% (6.375-6.385) (a) 8 % (b) 0.05 % (c) 8 X 10-3 % (d) 6.67 X 10-3 % (e) 3 % (f) 3 X 10-o % 4 30200m 1.004A 7.015N 0.003251m 0.03456kg 43000 ( ·. V Review 1 30.2 1.00 7.02 0.00325 0.0346 43000 30 1.0 7.0 0.0033 0.035 43000 Estimates first then calculator answers. (a) 6-14 ~ -8 (b) _2_.., 3 2.5 (c) 170 X 2 :,; 170 2 (e) 2 X 10 2 (f} lx 60.., I (a)-7.05 (d) 4820 (b) 4.37 (e) 214 (c) 197 (f) 1.15 (a) (i) 5.608xl0 7 (ii) 56.08 X 10 6 {b) (i) 9.78 X 10(ii) 97 .8 X 10-9 (c) 0.0000983 (d) 68300 (a) 0.5816kg (d) 15000m 2 (b) 3.567 X 10-3 (e) 12.96km/h (c) 95.2A (a) :MPE=0.005 (b) PE=0.0366% (a) 18 (d) .2. (b) .Jio (e)-3 (d) L 30 1 7 0.003 0.03 40000 4400.., 4400 1 60 2 8 3 4 5 .fi. (c) 2 (f) 10-2.../5 @ 1-19