Which expression is equivalent to cos (4x) + cos (2x)

Question

Lawson Price

Mathematics

20 March, 10:51

Which expression is equivalent to cos (4x) + cos (2x)

+3

Answers (1)

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Cohen Bailey · Answer 1

2*cos (3x) * cos (x)

Step-by-step explanation:

cos (4x) + cos (2x)

=cos (3x+x) + cos (3x-x)

Formula: cosx cosy=1/2 (cos (x+y) + cos (x-y))

Here, x will be 3x according to formula and y will be equal to x

So, cos (3x+x) + cos (3x-x)

=2*cos (3x) * cos (x)