Is cos(3θ)+cos(θ)=4cos^3(θ)-2cos(θ) ?

The answer to whether cos(3θ)+cos(θ)=4cos^3(θ)-2cos(θ) is True

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prove cos(3θ)+cos(θ)=4cos^3(θ)-2cos(θ)

prove

cos (3 θ) + cos (θ) = 4 cos^{3} (θ) - 2 cos (θ)

True

Solution steps

cos (3 θ) + cos (θ) = 4 cos^{3} (θ) - 2 cos (θ)

Manipulating left side

cos (3 θ) + cos (θ)

Rewrite using trig identities

= 4 cos^{3} (θ) - 2 cos (θ)

We showed that the two sides could take the same form

\Rightarrow True

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

cos^{7} (x) = (1 - sin^{2} (x))^{3} cos (x)

(1 + tan (θ))^{2} = sec^{2} (θ) + 2 tan (θ)

\frac{1 + cot ^{2} ( x )}{2 cot ( x )} = csc (2 x)

\frac{sin ( θ )}{1 - sin ^{2} ( θ )} = sec (θ) tan (θ)

Is cos(3θ)+cos(θ)=4cos^3(θ)-2cos(θ) ?
The answer to whether cos(3θ)+cos(θ)=4cos^3(θ)-2cos(θ) is True