Question

given: jklm is an isosceles trapezoid, kl || jm
prove: km ≅ jl
what is the missing reason in step 4?

1. jklm is an isosceles trapezoid, kl || jm
2. given
3. jk ≅ lm
4. definition of isosceles trapezoid
5. kl ≅ kl
6. reflexive property
7. ∠jkl ≅ ∠mlk

4.?

1. △jkl ≅ △mlk
2. sas ≅ theorem
3. km ≅ jl
4. cpctc

definition of linear pair
definition of congruence
base angles theorem
sufficient base angles theorem

Explanation:

In an isosceles trapezoid, the base angles are congruent. Since \(JKLM\) is an isosceles trapezoid with \(KL\parallel JM\), \(\angle JKL\) and \(\angle MLK\) are base angles. The base angles theorem states that in an isosceles trapezoid, base angles are congruent.

Answer:

base angles theorem