Is 1-2sin^2(y)+sin^4(y)=cos^4(y) ?

The answer to whether 1-2sin^2(y)+sin^4(y)=cos^4(y) is True

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prove 1-2sin^2(y)+sin^4(y)=cos^4(y)

prove

1 - 2 sin^{2} (y) + sin^{4} (y) = cos^{4} (y)

True

Solution steps

1 - 2 sin^{2} (y) + sin^{4} (y) = cos^{4} (y)

Manipulating left side

1 - 2 sin^{2} (y) + sin^{4} (y)

Apply Perfect Square Formula:

a^{2} - 2 ab + b^{2} = (a - b)^{2}

1 - 2 sin^{2} (y) + sin^{4} (y) = (1 - sin^{2} (y))^{2}

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

Use the Pythagorean identity:

1 = cos^{2} (y) + sin^{2} (y)

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

= (cos^{2} (y))^{2}

Simplify

(cos^{2} (y))^{2} : cos^{4} (y)

(cos^{2} (y))^{2}

Apply exponent rule:

(a^{b})^{c} = a^{b c}

= cos^{2 \cdot 2} (y)

Multiply the numbers:

2 \cdot 2 = 4

= cos^{4} (y)

= cos^{4} (y)

We showed that the two sides could take the same form

\Rightarrow True

Is 1-2sin^2(y)+sin^4(y)=cos^4(y) ?
The answer to whether 1-2sin^2(y)+sin^4(y)=cos^4(y) is True