The inverse tan of 1, ie tan^{-1} (1) is a very special value for the inverse tangent function. Remember that tan^{-1}(x) will give you the angle whose tan is x . Therefore, tan^{-1} (1) = the angle whose tangent is 1. It's also helpful to think of tangent

### The Value of the Inverse **Tan of 1**

As you can see below, the inverse tan^{-1} (1) is 45° or, in radian measure, Π/4. It is helpful to think of tangent as the ratio of sine over cosine, ie: . Therefore, tan(Θ) to equal 1, sin(Θ) and cos(Θ) must have the same value.

**So-When do sine and cosine have the exact same value?**

The answer is at and, of course, sine these trig functions are cyclical you can generalize