Math, asked by indubhushan1973, 5 months ago

(cos⁴A - sin⁴A) is equal to: *

Answers

Answered by Anonymous
0

\cos ^4\left(A\right)-\sin ^4\left(A\right)

=\left(\cos ^2\left(A\right)\right)^2-\left(\sin ^2\left(A\right)\right)^2

\mathrm{Apply\:Difference\:of\:Two\:Squares\:Formula:\:}x^2-y^2=\left(x+y\right)\left(x-y\right)

\left(\cos ^2\left(A\right)\right)^2-\left(\sin ^2\left(A\right)\right)^2=\left(\cos ^2\left(A\right)+\sin ^2\left(A\right)\right)\left(\cos ^2\left(A\right)-\sin ^2\left(A\right)\right)

=\left(\cos ^2\left(A\right)+\sin ^2\left(A\right)\right)\left(\cos ^2\left(A\right)-\sin ^2\left(A\right)\right)

=\left(\cos ^2\left(A\right)+\sin ^2\left(A\right)\right)\left(\cos \left(A\right)+\sin \left(A\right)\right)\left(\cos \left(A\right)-\sin \left(A\right)\right)

=\left(\cos \left(A\right)+\sin \left(A\right)\right)\left(\cos \left(A\right)-\sin \left(A\right)\right)\cdot \:1

=\left(\cos \left(A\right)+\sin \left(A\right)\right)\left(\cos \left(A\right)-\sin \left(A\right)\right)

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