Question

Answer 1

chứng minh nhé ạ 

 

Answer 2

\(sin^4a+cos^4a+2sin^2a.cos^2a=\left(sin^2a+cos^2a\right)^2=1^2=1\)

\(tan^2a-sin^2a.tan^2a=tan^2a\left(1-sin^2a\right)=tan^2a.cos^2a=\dfrac{sin^2a}{cos^2a}.cos^2a=sin^2a\)

Answer 3

a: ta có: \(\sin^4\alpha+\cos^4\alpha+2\cdot\sin^2\alpha\cdot\cos^2\alpha\)

\(=\left(\sin^2\alpha+\cos^2\alpha\right)^2\)

=1