CPM Homework Banner

Home > PC > Chapter 7 > Lesson 7.3.2 > Problem 7-113

7-113.

Draw a reference triangle in Quadrant 1 for both angles.

Label the 3rd side.
Both are pythagorean triples: 3,4,5 and 5,12,13

Find sin A from the triangle sides.

Find cos B from the triangle sides.

Use the sum and difference formula:
sin(A + B) = sinAcosB + cosAsinB

Use the sum and difference formula:
cos(A + B) = cosAcosB − sinAsinB