# Insanely easy question - trig functions, need a quick question answered

by andrew.c
 P: 47 1. The problem statement, all variables and given/known data I need to solve the equation $$cos 5x + cos 3x = cos x$$ Do the first two terms add together to be cos 8x? Then use double angle formula to solve?
HW Helper
P: 4,442
 Quote by andrew.c 1. The problem statement, all variables and given/known data I need to solve the equation $$cos 5x + cos 3x = cos x$$ Do the first two terms add together to be cos 8x? Then use double angle formula to solve?
No. cos 5x + cos 3x is not equal to cos8x.
Use formula to convert sum of trig. function to product form.

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