如果tanα=根号3,π<α<3π/2,那么cosα-sinα的值等于最好用正确符号 1+(tanα)^2=(secα)^2=1/(cosα)^2=4 cosα=-1/2 cosα-sinα=(1-tanα)*cosα=(根号3-1)/2 我看不懂
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![如果tanα=根号3,π<α<3π/2,那么cosα-sinα的值等于最好用正确符号 1+(tanα)^2=(secα)^2=1/(cosα)^2=4 cosα=-1/2 cosα-sinα=(1-tanα)*cosα=(根号3-1)/2 我看不懂](/uploads/image/z/2093464-64-4.jpg?t=%E5%A6%82%E6%9E%9Ctan%CE%B1%3D%E6%A0%B9%E5%8F%B73%2C%CF%80%EF%BC%9C%CE%B1%EF%BC%9C3%CF%80%2F2%2C%E9%82%A3%E4%B9%88cos%CE%B1-sin%CE%B1%E7%9A%84%E5%80%BC%E7%AD%89%E4%BA%8E%E6%9C%80%E5%A5%BD%E7%94%A8%E6%AD%A3%E7%A1%AE%E7%AC%A6%E5%8F%B7+1%2B%28tan%CE%B1%29%5E2%3D%28sec%CE%B1%29%5E2%3D1%2F%28cos%CE%B1%29%5E2%3D4+cos%CE%B1%3D-1%2F2+cos%CE%B1-sin%CE%B1%3D%281-tan%CE%B1%29%2Acos%CE%B1%3D%28%E6%A0%B9%E5%8F%B73-1%29%2F2+%E6%88%91%E7%9C%8B%E4%B8%8D%E6%87%82)
如果tanα=根号3,π<α<3π/2,那么cosα-sinα的值等于最好用正确符号 1+(tanα)^2=(secα)^2=1/(cosα)^2=4 cosα=-1/2 cosα-sinα=(1-tanα)*cosα=(根号3-1)/2 我看不懂
如果tanα=根号3,π<α<3π/2,那么cosα-sinα的值等于
最好用正确符号 1+(tanα)^2=(secα)^2=1/(cosα)^2=4 cosα=-1/2 cosα-sinα=(1-tanα)*cosα=(根号3-1)/2 我看不懂
如果tanα=根号3,π<α<3π/2,那么cosα-sinα的值等于最好用正确符号 1+(tanα)^2=(secα)^2=1/(cosα)^2=4 cosα=-1/2 cosα-sinα=(1-tanα)*cosα=(根号3-1)/2 我看不懂
简单的诱导公式,
tanα=√3,π<α<3π/2,是第三象限角,α=4π/3,(π+π/3),
cosα-sinα
=cos4π/3-sin4π/3
=-cosπ/3+sinπ/3
=-1/2+√3/2.
tan(读tanjite)对比斜rt△
cos(读koushaien)对比邻rt△
sec(读shaien)邻比斜rt△
1+(tanα)^2=(secα)^2=1/(cosα)^2=4 cosα=-1/2 cosα-sinα=(1-tanα)*cosα=(根号3-1)/2
“^”是什么?
设m=α-π,则:0<m<π/2
tanm=tan(α-π)=tanα=根号3
m=π/3
cosα-sinα=cos(π+m)-sin(π+m)
=-cosm+sinm
=[(根号3)-1]/2
cosa-sina/cos^2A+SIN^2A 都除以cosa 得1-tana/tana+cosa 然后算出cosa