# Homework Help: Trig functions squared

1. Jan 10, 2009

1. The problem statement, all variables and given/known data
cos2 0 = 1/2 (0 for angle)

2. Relevant equations

3. The attempt at a solution
I've never seen cos, sin, or tan to the power of anything before what do i do with the power?

2. Jan 10, 2009

### rock.freak667

What you could do is use an the identity $cos 2\theta=2cos^2\theta-1$

OR

put $cos\theta= \pm \frac{1}{\sqrt{2}}$ and then just solve $cos\theta= \frac{1}{\sqrt{2}}$ and $cos\theta= \frac{-1}{\sqrt{2}}$

3. Jan 10, 2009

### Unco

Perhaps you are unfamiliar with the notation: $$\cos^2{\theta}$$ means $$(\cos{\theta})^2$$.

4. Jan 10, 2009

### Delphi51

You don't say what you are supposed to do with it!
You could find the value of the angle easily by taking the square root of both sides to get
cos \\theta =
on the left.

5. Jan 10, 2009

### Delphi51

You don't say what you are supposed to find! Maybe the angle?
If you take the square root of both sides you'll get

cos 0
on the left

Can someone tell me how to get a "theta" in this forum?

6. Jan 10, 2009

### NoMoreExams

You can just hit quote and see how others have done it but if you use [ tex] ... [/ tex] tags (obviously without spaces) then to get the symbol theta you would just use \theta

7. Jan 10, 2009

### Delphi51

Thanks! Hope this works . . .
cos $$\theta$$

8. Jan 10, 2009

### NoMoreExams

Instead of doing cos$$\theta$$. I think this looks much nicer:

$$\cos(\theta)$$

You can click on what you are trying to see the TeX "code" for and a box will open telling you the "code"

9. Jan 10, 2009

### Delphi51

Thanks again, NoMoreExams. I actually saw that click on trick before, but it didn't show the [ tex] so I couldn't get it to work.