SOLUTION: If angle A and angle B are acute angles of right triangle ABC, what is the value of sin A

SOLUTION: If angle A and angle B are acute angles of right triangle ABC, what is the value of sin A - cos B ?

Question 130116: If angle A and angle B are acute angles of right triangle ABC, what is the value of sin A - cos B ?
Answer by jim_thompson5910(35256) (Show Source): You can put this solution on YOUR website!
If you draw a picture, you'll notice that angle A and B are connected. If you know the measure of angle A, then angle B is: B=90-A

So

also looks like

Now if you look at the list of identities, you'll see one that reads:

So our expression becomes

Just replace with

and the expression evaluates to 0

So

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