# Please explain

1. Mar 10, 2006

### rachael

What does "simplify" means in this case:
Simplify each of the following:
1. sin(3pi/2-x)

2. Mar 10, 2006

### VietDao29

Do you mean something like this:
$$\sin \left( \frac{3 \pi}{2 - x} \right)$$?
If you mean that, then I don't think it can be simplified any more.

3. Mar 10, 2006

### rachael

nope i mean sin [(3pi/2)-x]

4. Mar 10, 2006

### VietDao29

Ahh, I see. I'll give you some hints. Do you know something like:
$$\sin (\pi + x) = - \sin x$$ and
$$\sin \left( \frac{\pi}{2} - x \right) = \cos x$$?

5. Mar 10, 2006

### HallsofIvy

In other words, "simplify" here means "write in a simpler form" which would be something like Asin(x)+ Bcos(x) rather than sin($\theta$+x). In my opinion you would certainly be justified in arguing whether or not that is simpler but it is clearly what is intended.

6. Mar 10, 2006

### topsquark

In general:
$$sin(A \pm B)=sinA \, cosB \pm sinB \, cosA$$
$$cos(A \pm B)=cosA \, cosB \mp sinA \, sinB$$

-Dan

7. Mar 21, 2006

### rachael

thank you......

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