### Home > A2C > Chapter 1 > Lesson 1.2.1 > Problem 1-61

1-61.

For each diagram below, write and solve an equation to find the value of each variable. Give your answer to part (d) in both radical and decimal form. For a reminder of the trigonometry ratios, refer to the Math Notes box for this lesson.

Use your calculator to compute

. Does your answer seem reasonable? If not, verify that your calculator is in degree mode.

Follow the steps in part (a).

How can you "undo" cosine?

An angle is not marked, just three sides. What formula uses three sides of a right triangle?

Pythagorean Theorem