The double angle formula for the sine is

The right hand side is exactly your expression, where 
So, rewriting the expression from right to left, we have

Answer:
it is D
Step-by-step explanation:
the ratio is 1.5 so multiply 15 by 1.5
Answer:
3a-10
Step-by-step explanation:
<h2>MAYBE IT HELPS</h2>
Answer:
(6, 12)
Step-by-step explanation:
{ 3x - y = 6
{ x - 2y = -18
by using elimination:
6x -2y=12
x - 2y= -18
________-
5x = 30
x = 6
y = 18-6 = 12
the solutions = {(6, 12)}