College Algebra & Trigonometry, 2018a

8.3. SOLVING TRIANGLES 363
Example 3
Solve the triangle. Round side lengths to the nearest 100 th and angles to the nearest
10 th of a degree.
22 ◦ 10 ′
40
If we convert the angle 22 ◦ 10 ′ to 22.16 ◦ , then the other acute angle in the right
triangle is 90 ◦ − 22.16 ◦ =67.83 ◦ or 67 ◦ 50 ′ .
Finding the remaining sides requires the use of either the cosine or tangent function.
cos 22.16 ◦ = 40
c
Approximating cos 22.16 ◦ on a calculator:
0.9261 ≈ 40
c
Next we need to multiply on both sides by c:
c ∗ 0.9261 ≈ 40
c ∗c
0.9261c ≈ 40
Then divide on both sides by 0.9261:
0.9261c
0.9261 ≈ 40
0.9261
c ≈ 43.2