Because ABCD is an isosceles trapezoid, the angles A and D are congruent.
BA and CD are congruent (given) and AD is congruent to itself (reflexive property).
Then triangles BAD and CDA form a pair of SAS triangles, so they are congruent.
BD and CA are corresponding parts in those triangles, so they are congruent (CPCTC).
I'm not 100% but I'm pretty sure the answer is True
Answer:
x = 8/21
Step-by-step explanation:
use cosine ratio
