### Home > GC > Chapter 5 > Lesson 5.1.4 > Problem 5-40

5-40.

** ** in the triangle at right. She lost her scientific calculator, but luckily her teacher told her that

Write an equation that Estelle could use to solve for

.

Use the Triangle Angle Sum Theorem to calculate the missing angle, this means all the angles in a triangle total

Place a "" on the missing side. Write the trigonometric ratios for the angle, reference the Math Note box in Lesson 5.1.2 for extra help.

Which equation can be used to solve for ?

Without a calculator, how could Estelle find

? Explain.