Question

Biết

\(\sin\alpha=\frac{8}{17}\), Tính B=\(4\sin^2\alpha+3\cos^2\alpha\)

Answer 1

Ta có \(\sin^2\alpha+\cos^2\alpha=1\Leftrightarrow\cos^2\alpha=1-\sin^2\alpha=1-\left(\frac{8}{17}\right)^2=\frac{225}{289}\)

Vậy B=\(4.\left(\frac{8}{17}\right)^2+3.\frac{225}{289}=\)\(\frac{931}{289}\)

Answer 2

huhu. Mẹ ơi! Làm sao thắng nó!!!