Page 36 - Math Course 3 (Book 2)

Properties of Trapezoids

MO. 7 - L6b
Let’s Begin

Isosceles Trapezoids

Identify Isosceles Trapezoids

Vocabulary A-Z Example

Let us learn some vocabulary
The top of this work station appears to be two
adjacent trapezoids. Determine if they are
isosceles trapezoid isosceles trapezoids.
It is called an Isosceles trapezoid if the sides that
aren’t parallel are equal in length and both angles
coming from a parallel side are equal

A B

Each pair of base angles is congruent, so the legs
are the same length.

Answer Both trapezoids are isosceles
D C

THEOREMS Identify Trapezoids

Isosceles Trapezoid Example

7.18 Each pair of base angles of an isosceles
trapezoid are congruent.
ABCD is a quadrilateral with vertices A(5, 1),
B(–3, –1), C(–2, 3), and D(2, 4). Verify that
7.19 The diagonals of an isosceles trapezoid are ABCD is a trapezoid.
congruent

Example: A B C(–2, 3) D(2, 4)

∠DAB ≅ ∠CBA
∠ADC ≅ ∠BCD A(5, 1)
AC ≅ BD

D C B(–3, –1)

A quadrilateral is a trapezoid if exactly one pair of
opposite sides are parallel. Use the Slope Formula.

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