Is cos^2(x)-sin^2(y)=1-2sin^2(y) ?

The answer to whether cos^2(x)-sin^2(y)=1-2sin^2(y) is False

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prove cos^2(x)-sin^2(y)=1-2sin^2(y)

prove

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

False

Solution steps

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

Show that the two sides are not equal

For

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

plug in

x = 0

For

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

plug in

y = 1

cos^{2} (0) - sin^{2} (1) = 0.29192 \dots

cos^{2} (0) - sin^{2} (1)

Refine to a decimal form

= 0.29192 \dots

1 - 2 sin^{2} (1) = - 0.41614 \dots

1 - 2 sin^{2} (1)

Refine to a decimal form

= - 0.41614 \dots

The two sides are not equal

\Rightarrow False

Is cos^2(x)-sin^2(y)=1-2sin^2(y) ?
The answer to whether cos^2(x)-sin^2(y)=1-2sin^2(y) is False