1, arcsine (-x)=- arcsine X.

2、arccos(-x)=π-arccosx .

3. Arctangent (-x)=- arctangent.

4、arccot(-x)=π-arccotx .

5、arcs inx+arc cosx =π/2 = arctanx+arccotx .

6、sin(arc sinx)= x = cos(arc cosx)= tan(arc tanx)= cot(arc cotx)。

7. when x ∈ [-π/2, π/2], there is arcsin (sinx) = X.

8. When x ∈ [0, π], arccos (cosx) = x.

9、x∑(——π/2，π/2)，arctan(tanx)=x .

10、x∈(0，π)，arccot(cotx)=x .

1 1、x÷0，arctanx=arctan 1/x .

12, if (arctanx+arctany) ∈ (-π/2, π/2), then arctanx+arctany = arctan (x+y/1-xy).