# Transforming sin(x) into cos(x)*tan(x): sin2costan

### 5.23.15 Transforming sin(x) into cos(x)*tan(x): sin2costan

The sin2costan command replaces sin(x) by cos(x)tan(x) in an expression.

- sin2costan takes one argument:
  expr, an expression containing trigonometric functions.
- sin2costan(expr) returns expr with anything of the form sin(x) replaced by cos(x)tan(x).

#### Example.

Input:

sin2costan(sin(2*x))

Output:

tan | ⎛ ⎝ | 2 x | ⎞ ⎠ | cos | ⎛ ⎝ | 2 x | ⎞ ⎠