Question

Given ΔABC, m∠A = 50°, m∠B = 60°, and a = 7. Find c.

Answer 1

D) 8.6

Explanation:

The Law of Sines tells you ...

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

The sum of angles in a triangle tells you ...

C = 180° -A -B = 180° -50° -60° = 70°

Then ...

c = a·sin(C)/sin(A) = 7·sin(70°)/sin(50°) ≈ 8.6 . . . . . above equation multiplied by sin(C)

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There are apps available for phone or tablet for solving triangles. Many graphing calculators have functions that will do the same. Also, there are on-line triangle solvers that will give you the answer.

We include the working here because you're supposed to know how to work the problem. If all you want is the answer, that can be found faster a number of different ways.