Question

Verify that cos x+(pi/2)=-sin x

Answer 1

this mean
\[\cos(x+\frac{\pi}{2})=-\sin(x)\] right?

Answer 2

Yes

Answer 3

you know the addition angle formula for cosine?

Answer 4

Is that the same thing as sum and difference

Answer 5

@satellite73

Answer 6

@satellite73 are you there

Answer 7

yeah the "sum" formula if you like the word 'sum' instead of "addition" same thing

Answer 8

Ok so i believe it's cos(A+B)=cos A cos B - sin A sin B, right

Answer 9

yes

Answer 10

replace \(A\) by \(x\) and \(B\) by \(\frac{\pi}{2}\) and it will drop right out

Answer 11

So cos (x+pi/2)= cos x cos pi/2 - sin x sin pi/2 and then I would solve that

Answer 12

yes

Answer 13

you get it in one step

Answer 14

Oh ok I was trying to do it a different way that's where I was confused thanks.

Answer 15

yw