Question

***WILL MEDAL***
What is the missing reason in steps 7 and 8 of the proof?
Given: ∆ABC with AB = c, BC = a, AC = b
Prove: a/sin A= b/sin B= c/sin C
7. In ∆BAE, AE = c sin B
8. In ∆CAE, AE = b sin C
A. definition of cosine in right triangle
B. definition of sine in right triangle
C. definition of tangent in right triangle
D. Corresponding sides of congruent triangles are equal.
E. definition of equilateral triangle