In triangle ABC, B = 90 degrees, and AC = 13 cm.

In triangle ABC, B = 90 degrees, and AC = 13 cm.

Determine:

A) BC if C = 17 degrees. B) A if BC = 6cm .

A) If C = 17°  then  A = 90 -17  = 73°

By the Law of Sines

BC / sin 73  =  AC / sin90

BC / sin 73 = 13/1

BC = 13sin(73)    ≈  12.4

B)  A if BC = 6

Again by the Law of Sines

sin A / BC  = sin90 / AC

sin A / 6 = 1 /13

sin A = 6/13      take the sine inverse to find angle A

arcsin (6/13) = A ≈ 27.5°