Asked Mar 8, 2020

use an addition or subtraction formula to simplify the following equation, then find all solutions in the interval [0. radian/4].

equation: cosx cos7x-sinx sin7x=0

its an addition formula for cosine, so simplified it would be cos(8x)

finding all solutions, and putting them in interval form is what I am confused with


Expert Answer

Step 1

The addition formula for cosine is given by

cos(a + b) = cos a cos b – sin a sin b

Step 2

Use the addition formula for cosine and simplify the given equation as follows.

Calculus homework question answer, step 2, image 1


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