TRIGONOMETRY:SUM-TO-PRODUCT AND PRODUCT-TO-SUM FORMULAS

The formulas below will enable us to change a sum or difference to a product.

Example 1

Express sin11x + sin5x as a product.

Solution:

Example 2

Express cos5x – cos4x as a product.

Solution:

The formulas below will enable us to change a product to a sum or difference.

Example 3

Express sin6xsin4x as a sum or difference.

Solution:

Example 4

Try these problems

QUESTIONS

ANSWERS

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4.