Question

giúp mk câu này nhé!!!! mk cần gấp

 

Answer 1

Có \(cos^2\alpha=1-sin^2\alpha=\dfrac{16}{25}\)

\(A=5sin^2\alpha+6cos^2\alpha=5\left(sin^2\alpha+cos^2\alpha\right)+cos^2\alpha=5+\dfrac{16}{25}=\dfrac{141}{25}\)