Question

Solve the triangle if C = 120°, B = 50°, and c = 15.
Find A.
Round to the nearest tenth.

Answer 1

• A = 10°
• a = 3.0
• b = 13.3

Explanation:

The law of sines is useful. First we need to find the remaining angle.

A + B + C = 180°

A = 180° - B - C = 180° -50° -120°

A = 10°

Now we can find the other two sides.

a/sin(A) = c/sin(C)

a = c(sin(A)/sin(C)) = 15(sin(10°)/sin(120°)) ≈ 3.00767 ≈ 3.0

b/sin(B) = c/sin(C)

b = c(sin(B)/sin(C)) = 15(sin(50°)/sin(120)) ≈ 13.2683 ≈ 13.3

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The solution is A = 10°, a = 3.0, b = 13.3.