### Home > CCG > Chapter 5 > Lesson 5.3.5 > Problem5-126

5-126.

Solve for the missing side lengths and angles in the triangle below.

This triangle has known values for $\text{SAS}$ (side-angle-side) so will need to be solved using the Law of Cosines.
Refer to the Math Notes box in Lesson 5.3.3 if you need help remembering the Law of Cosines.

Solve for c.

$c^2=10^2+17^2-2(10)(17)\text{cos }45º$

After finding the length of $c$, the Law of Sines can be used to to find the measure of $∠A$.
Refer to the Math Notes box in Lesson 5.3.2 for the Law of Sines.

$\frac{\text{sin }A}{10}=\frac{\text{sin }45}{c}$

Use the Triangle Angle Sum Theorem to find the measure of $∠B$.