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

To solve this problem, you can make a proportion:
3/900 = x/2100
In this case, the x represents the pounds that will be needed to cover 2,100 feet.
The first step is to cross multiply like this:
3 * 2100 = 900 * x
Now you can simply the equation.
6300 = 900x
Now you divide both sides by 900 to cancel it out.
7 = x
So, your answer is 7 pounds.
Answer:
Hope you find the help you need on this sorry , i couldnt find the answer :( good luck !!
Step-by-step explanation:
Answer:
10-8=2 i think
Step-by-step explanation:
Answer:
hey46
Step-by-step explanation:
46