advertisement

7­39. 10 sides b: regular decagon 7­40. If the diagonals intersect at E, then BE = 12 mm, since the diagonals are perpendicular bisectors. Then ΔABE is a right triangle and AE = √152 ­ 122 = 9 mm. Thus, AC = 18 mm. 7­41. Yes, she is correct. One way: Show that the lengths on both sides of the midpoint are equal and that (2, 4) lies on the line that connects (­3, 5) and (7, 3) . 7­42. (a) and (c) are correct because if the triangles are congruent, then corresponding parts are congruent. Since alternate interior angles are congruent, then AB // DE . 7­43. AB = √40 ≈ 6.32, BC = √34 ≈ 5.83, therefore C is closer to B. 1 Warm up Write down the method and meanings on page 346 and write the definition down of a regular polygon on page 351 2 3 7 ­ 43 A C B 4 Lesson 7.2.1 What can congruent triangles tell me? Objective: students will be introduced to proofs and will learn more properties of parallelograms and kites NOTE: first semester we studied triangles, now we are going to switch to QUADRILATERALS In­class 7­44 learning properties about parallelograms Part d) make a flowchart for showing that the two triangles are congruent VERY IMPORTANT THAT YOU UNDERSTAND THIS LEAVE ROOM ABOVE YOUR FLOWCHART TO ADD THINGS 7­45 There are a few things we need to add, once most groups are done I will go over this with the whole class 7­46 Let's look at a KITE 7­47 looking at the other diagonal of a kite and using it to make a congruency flowchart 7­48 write down the properties you learned about parallelograms and kites today A B 7­44 D C 5 7­45 AB // CD AD // BC Given <ADB ≅ <CBD If lines are //, then alternate interior angles are ≅ Given <ABD ≅ <CDB BD ≅ BD Reflexive property If lines are //, then alternate interior angles are ≅ ΔADB ≅ ΔCDB ASA ≅ 6 C 7 ­ 47 A AC ≅ BC C B A D B CD ≅ CD m<ADC = m<BCD Given reflexive property Given ΔADC ≅ ΔBCD SAS≅ AD ≅ DB We will learn this reason tomorrow 7 Homework: In Class 7 ­ 44 to 7 ­ 47 Review and Preview 7 ­ 49 to 7 ­ 53 FILL IN TOOLKIT FOR PARALLELOGRAM AND KITE 8