8.5 Trapezoids
Vocabulary What You'll Learn Trapezoids What You'll Learn You will learn to identify and use the properties of trapezoids and isosceles trapezoids. Vocabulary 1) Trapezoid
A trapezoid is a ____________ with exactly one pair of ____________. Trapezoids A trapezoid is a ____________ with exactly one pair of ____________. quadrilateral parallel sides The parallel sides are called ______. bases The non parallel sides are called _____. legs base T P A R Each trapezoid has two pair of base angles. leg leg base angles T and R are one pair of base angles. P and A are the other pair of base angles. base
The median of a trapezoid is parallel to the _____, bases Trapezoids Theorem 8-13 The median of a trapezoid is parallel to the _____, bases and the length of the median equals _______________ of the lengths of the bases. one-half the sum C N B D M A
Find the length of median MN in trapezoid ABCD if AB = 16 and DC = 20 Trapezoids Find the length of median MN in trapezoid ABCD if AB = 16 and DC = 20 16 C N D M B A 18 20
If the legs of a trapezoid are congruent, the trapezoid is an Trapezoids If the legs of a trapezoid are congruent, the trapezoid is an _________________. isosceles trapezoid In lesson 6 – 4, you learned that the base angles of an isosceles triangle are congruent. There is a similar property of isosceles trapezoids.
Each pair of __________ in an isosceles trapezoid is congruent. Trapezoids Theorem 8-14 Each pair of __________ in an isosceles trapezoid is congruent. base angles Z Y X W
Find the missing angle measures in isosceles trapezoid TRAP. Trapezoids Find the missing angle measures in isosceles trapezoid TRAP. T P A R 60° P A Theorem 8 – 14 120° 120° mP = mA 60 = mA T R Theorem 8 – 14 60° P + A + 2(T) = 360 60 + 60 + 2(T) = 360 120 + 2(T) = 360 2(T) = 240 T = 120 R = 120
Trapezoids End of Section 8.5