Question

How do you evaluate `arctan(1/2)`?

Answer 1

The `arctan(1/2)` is the angle `theta` such that `tan(theta) = 1/2`

We can imagine such an angle in the first quadrant as being part of a right-triangle with opposite side `=1`, adjacent side `=2`, and hypotenuse `=sqrt(5)`.

Unfortunately this is not one of the standard angles and the only way (as far as I can tell) to evaluate it is to use a calculator (or something similar) to look-up:

`arctan(1/2) = 0.463648 " radians" = 26.56505^@`