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=4cosα=-1/2cosα-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=4cosα=-1/2cosα-sinα=(1-tanα)*cosα=(根号3-1)/2我看不懂