# Transforming arcsin into arccos: asin2acos

### 5.23.9 Transforming arcsin into arccos: asin2acos

The asin2acos command transforms any asins in an expression to acoss, using the identity arcsin(x) = π/2 − arccos(x).

- asin2acos takes one argument:
  expr, an expression containing inverse trigonometric functions.
- asin2acos(expr) returns expr with any asins replaced by the appropriate acoss.

#### Example.

Input:

asin2acos(acos(x)+asin(x))

Output (after simplification):

π
2