Question

Let A ABC be defined so that angle A is a right angle and the measure of

angle B is 60°. Side AC = 20. What is the value of BC?

Answer 1

You can use the law of sines (a/sin(A) = b/sin(B) = c/sin(C)) to work it out. b/sin(B) = 20/sin(60) = 20/(√(3)/2) = 40/√3. Since a/sin(A) is equal to b/sin(B) which is equal to 40/√3, a/Sin(A) must also equal 40/√3. A = 90º, and sin(90) = 1, so a, must be equal to 40/√3.

Answer: 40/√3