Question

How do you simplify the expression `sin(arctan(x/5))`?

Answer 1

`+-x/sqrt(x^2+25)`.

Explanation:

Let `a = arc tan (x/5)`.

Then, `tan a = x/5 >=<0` according as x>=<0#

Befittingly, the quadrant for a has to be chosen.

So, the given expression `= sin a = +-x/sqrt(x^2+25)`.