Find sin beta if cos beta = 3/5

From pythogeron therom 5, 12,13 are sides of right angle triangle.

As you can see here 13 is hypotenuse, 5 is adjacent side, 12 is opposite side.

From pythogeron therom 37, 12, 35 are sides of right angle triangle.

So 37 is hypotenuse, 35 is an adjoining side, 12 is opposite side.