Answers 8.2 plus review

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Agenda

• Go over homework.

• Go over Exploration 8.13: more practice

• A few more details--they are easy.

• Lots more practice problems.

• Study hard! And bring a ruler and protractor.

Homework 8.2

• 1c. Hexagon, 6 sides, non-convex, no congruent sides, 2 acute angles, 3 obtuse angles, 1 reflex angle, no parallel sides, no right angles…

Homework 8.2

• 4. Shape # diagonals

– Quadrilateral

– Pentagon

– Hexagon

– Octagon

2

5

9

20

– N-gon

– each vertex (n) can connect to all but 3 vertices

(itself, left, and right). So, n(n-3).

– But now diagonals have been counted twice. So n(n-3)/2

Homework 8.2

• 11. Adjacent, congruent sides. Can be true for:

• Trapezoid

• Square

• Rhombus

• Non-convex kite

• Convex kite.

Homework 8.2

• 18a

• Scalene obtuse

Homework 8.2

• 18b

• Equilateral Isosceles

Homework 8.2

• 18c.

• Parallelogram rectangle

Homework 8.2

• 18b

• rectangle rhombus

Quadrilaterals

• Look at Exploration 8.13. Do 2a, 3a - f.

• Use these categories for 2a:

– At least 1 right angle

– 4 right angles

– 1 pair parallel sides

– 2 pair parallel sides

– 1 pair congruent sides

– 2 pair congruent sides

– Non-convex

Exploration 8.13

• Let’s do f together:

• In the innermost region, all shapes have 4 equal sides.

• In the middle region, all shapes have 2 pairs of equal sides. Note that if a figure has 4 equal sides, then it also has 2 pairs of equal sides. But the converse is not true.

• In the outermost region, figures have a pair of equal sides. In the universe are the figures with no equal sides.

8.13 2a

• At least 1 right angle: A, E, G, J, O, P

• 4 right angles: J, O, P

• At least 1 pair // lines: E, F, J - P

• 2 pair // lines: J - P

• At least 1 pair congruent sides: not A, B, C, E

• 2 pair congruent sides: G - P

• Non-convex: I

8.13

• 3a: at least 1 obtuse angle (or no right angle,

1 obtuse and 1 acute angle ), 2 pair parallel sides (or 2 pair congruent sides)

• 3b: at least 1 pair parallel sides, at least 1 pair congruent sides

• 3c: at least 1 pair sides congruent, at least 1 right angle

8.13

• 3d: kite , parallelogram

• 3e: LEFT: exactly 1 pair congruent sides, RIGHT: 2 pair congruent sides,

BOTTOM: at least 1 right angle

• 3f: Outer circle: 1 pair congruent sides, Middle circle: 2 pair congruent sides, Inner circle: 4 congruent sides

Try these now

• What are the attributes?

parallelogram

1 right angle

E, G,

O

P

K, L,

M, N

Try these now

• What are the attributes?

Trapezoid At least 1 right angle

E

D, F

G, J,

O, P

Try this one

• What are the attributes?

4 right angles

At least 1 right angle

J, O, P

E, G

Discuss answers to

Explorations 8.11 and 8.13

• 8.11

• 1a - c

• 3a: pair 1: same area, not congruent; pair 2: different area, not congruent;

• Pair 3: congruent--entire figure is rotated 180˚.

Warm Up

• Use your geoboard to make:

• 1. A hexagon with exactly 2 right angles

• 2. A hexagon with exactly 4 right angles.

• 3. A hexagon with exactly 5 right angles.

• Can you make different hexagons for each case?

Warm-up part 2

• 1. Can you make a non-convex quadrilateral?

• 2. Can you make a non-simple closed curve?

• 3. Can you make a non-convex pentagon with 3 collinear vertices?

Warm-up Part 3

• Given the diagram at the right, name at least 6 different polygons using their vertices.

A

B

G

C

F

D

E

A visual representation of why a triangle has 180˚

• Use a ruler and create any triangle.

• Use color--mark the angles with a number and color it in.

• Tear off the 3 angles.

• If the angles sum up to 180˚, what should I be able to do with the 3 angles?

Diagonals, and interior angle sum ( regular )

• Triangle

• Quadrilateral

• Pentagon

• Hexagon

• Heptagon (Septagon)

• Octagon

• Nonagon (Ennagon)

• Decagon

11-gon

Dodecagon

Congruence vs. Similarity

Two figures are congruent if they are exactly the same size and shape.

Think: If I can lay one on top of the other, and it fits perfectly, then they are congruent.

Question: Are these two figures congruent?

Similar: Same shape, but maybe different size.

Let’s review

• Probability:

• I throw a six-sided die once and then flip a coin twice.

– Event?

– Possible outcomes?

– Total possible events?

– P(2 heads)

– P(odd, 2 heads)

– Can you make a tree diagram?

Can you use the Fundamental Counting

Principle to find the number of outcomes?

• Probability:

• I have a die: its faces are 1, 2, 7, 8, 9, 12.

• P(2, 2)--is this with or without replacement?

• P(even, even) =

• P(odd, 7) =

• Are the events odd and 7 disjoint? Are they complementary?

Combinations and

Permutations

• These are special cases of probability!

• I have a set of like objects, and I want to have a small group of these objects.

• I have 12 different worksheets on probability.

Each student gets one:

– If I give one worksheet to each of 5 students, how many ways can I do this?

– If I give one worksheet to each of the 12 students, how many ways can I do this?

More on permutations and combinations

• I have 15 french fries left. I like to dip them in ketchup, 3 at a time. How may ways can I do this?

• I am making hamburgers: I can put 3 condiments: ketchup, mustard, and relish, I can put 4 veggies: lettuce, tomato, onion, pickle, and I can use use 2 types of buns: plain or sesame seed. How many different hamburgers can I make?

• Why isn’t this an example of a permutation or combination?

When dependence matters

• If I have 14 chocolates in my box: 3 have fruit, 8 have caramel, 2 have nuts, one is just solid chocolate!

• P(nut, nut)

• P(caramel, chocolate)

• P(caramel, nut)

• If I plan to eat one each day, how many different ways can I do this?

Geometry

• Sketch a diagram with 4 concurrent lines.

• Now sketch a line that is parallel to one of these lines.

• Extend the concurrent lines so that the intersections are obvious.

• Identify: two supplementary angles, two vertical angles, two adjacent angles.

• Which of these are congruent?

Geometry

• Sketch 3 parallel lines segments.

• Sketch a line that intersects all 3 of these line segments.

• Now, sketch a ray that is perpendicular to one of the parallel line segments, but does not intersect the other two parallel line segments.

• Identify corresponding angles, supplementary angles, complementary angles, vertical angles, adjacent angles.

Name attributes

• Kite and square

• Rectangle and trapezoid

• Equilateral triangle and equilateral quadrilateral

• Equilateral quadrilateral and equiangular quadrilateral

• Convex hexagon and non-convex hexagon.

Consider these triangles

acute scalene, right scalene, obtuse scalene, acute isosceles, right isosceles, obtuse isosceles, equilateral

– Name all that have:

– At least one right angle

– At least two congruent angles

– No congruent sides

Consider these figures:

Triangles: acute scalene, right scalene, obtuse scalene, acute isosceles, right isosceles, obtuse isosceles, equilateral

Quadrilaterals: kite, trapezoid, parallelogram, rhombus, rectangle, square

Name all that have:

At least 1 right angle

At least 2 congruent sides

At least 1 pair parallel sides

At least 1 obtuse angle and 2 congruent sides

At least 1 right angle and 2 congruent sides

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