Is sin^2(a)-cos^2(a)=1-2cos^2(a) ?

The answer to whether sin^2(a)-cos^2(a)=1-2cos^2(a) is True

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prove sin^2(a)-cos^2(a)=1-2cos^2(a)

prove

sin^{2} (a) - cos^{2} (a) = 1 - 2 cos^{2} (a)

True

Solution steps

sin^{2} (a) - cos^{2} (a) = 1 - 2 cos^{2} (a)

Manipulating left side

sin^{2} (a) - cos^{2} (a)

Rewrite using trig identities

= 1 - 2 cos^{2} (a)

We showed that the two sides could take the same form

\Rightarrow True

tan (2 A) - 2 tan (2 A) sin^{2} (A) = sin (2 A)

\frac{1}{tan ( x ) csc ( x )} = cos (x)

tan (4 θ) + tan (2 θ) = sec (4 θ) - sec (2 θ)

tan^{2} (x) csc^{2} (x) - 1 = tan^{2} (x)

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

Is sin^2(a)-cos^2(a)=1-2cos^2(a) ?
The answer to whether sin^2(a)-cos^2(a)=1-2cos^2(a) is True