rút gọn bt :cos^2∝ +cos^2∝.sin^2∝+sin^4∝ 01/07/2021 Bởi Genesis rút gọn bt :cos^2∝ +cos^2∝.sin^2∝+sin^4∝
$\cos^2\alpha+\cos^2\alpha.\sin^2\alpha+\sin^4\alpha$ $=\cos^2\alpha+\sin^2\alpha(\cos^2\alpha+\sin^2\alpha)$ $=\cos^2\alpha+\sin^2\alpha$ $=1$ Bình luận
Đáp án: Giải thích các bước giải: `cos^2 \alpha+cos^2 \alpha. sin^2 \alpha+sin^4 \alpha` `= sin^4 \alpha+sin^2 \alpha. cos^2 \alpha+cos^2 \alpha` `=sin^4 \alpha+2sin^2 \alpha. cos^2 \alpha+cos^4 \alpha-cos^4 \alpha-sin^2 \alpha. cos^2 \alpha+cos^2 \alpha` `=(sin^2 \alpha+cos^2 \alpha)^2-cos^4 \alpha+cos^2 \alpha(1-sin^2 \alpha)` `=1-cos^4 \alpha+cos^2 \alpha. cos^2 \alpha` `=1-cos^4 \alpha+cos^4 \alpha` `=1` Bình luận
$\cos^2\alpha+\cos^2\alpha.\sin^2\alpha+\sin^4\alpha$
$=\cos^2\alpha+\sin^2\alpha(\cos^2\alpha+\sin^2\alpha)$
$=\cos^2\alpha+\sin^2\alpha$
$=1$
Đáp án:
Giải thích các bước giải:
`cos^2 \alpha+cos^2 \alpha. sin^2 \alpha+sin^4 \alpha`
`= sin^4 \alpha+sin^2 \alpha. cos^2 \alpha+cos^2 \alpha`
`=sin^4 \alpha+2sin^2 \alpha. cos^2 \alpha+cos^4 \alpha-cos^4 \alpha-sin^2 \alpha. cos^2 \alpha+cos^2 \alpha`
`=(sin^2 \alpha+cos^2 \alpha)^2-cos^4 \alpha+cos^2 \alpha(1-sin^2 \alpha)`
`=1-cos^4 \alpha+cos^2 \alpha. cos^2 \alpha`
`=1-cos^4 \alpha+cos^4 \alpha`
`=1`