Hard question please help. I had to repost because last time I wanted to give more points but I forgot to. If find what is.

Best Answer gets the reaming 15!
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Use the angle sum identities to expand and :

Use the double angle identity to expand :

So we have

Then divide the first expression by and the second by :

Squaring these gives

Subtract the second expression from the first to get the original equation. The terms cancel, leaving us with

Now, notice that

and

because and .

So we're left with

7

step-by-step explanation: