F4,,A-MATHS,,TRIGO!!,,急問喔

|cosx|-|sinx|=sinx-cosx
0<=x<= π
若0<=x<= π/2
則 cosx 及 sinx 均為正值，則
|cosx|-|sinx|=sinx-cosx
cosx – sinx = sinx – cosx [全式除 cosx]
1 – tanx = tanx – 1
2tanx = 2
tanx = 1
x = 45o
若π/2<=x<= π
則 cosx 為負值 及 sinx 為正值，則
|cosx|-|sinx|=sinx-cosx
-cosx – sinx = sinx – cosx [全式除 cosx]
-1 – tanx = tanx – 1
2tanx = 0
tanx = 0
x =180o