Cosx= 1 after derivation, and x=2kπ after solution.

And-1≤x=sinX≤ 1,

So x=0,

So there is only one intersection (0,0).

According to the meaning of the question, the slope of y=x is 1.

X is between -π/2 and π/2,

Where the slope of f(x)=sinX is 0≤k=cosX≤ 1,

When k= 1 and x=0,

So there is only one intersection (0,0).

3. Take X and -π/2, 0 and π/2 when drawing.