Equivalent expression of sin(arctan (x/3))

Step-by-step explanation:

Let .

Then .

Construct a right triangle.

Make one of the non-right angles .

Recall is equal to the ratio of the side that is opposite to to the side that is adjacent to .

This means opposite side while adjacent side since .

We can find the hypotenuse by using the Pythagorean Theorem.

Take the square root of both sides:

.

Recall is equal to the ratio of the side that is opposite to to the hypotenuse.

-->Because we let the inside equal .

-->Because