# A simple trig. problem.

1. Nov 22, 2005

### dragon513

Q. Solve: secx=-5.2
x is greater than or equal to zero and less than or equal to 2π

I got 1.76 and 4.52, but answer key only has 1.76.

Am I not right?

2. Nov 22, 2005

### opticaltempest

I find the same answers as you do when I do a quick check using my TI-89. Hmmm

3. Nov 23, 2005

### VietDao29

4. Nov 23, 2005

### dragon513

Thank you!

5. Nov 23, 2005

### Ouabache

Once you had the first solution 1.76, how did you find the 2nd one?

6. Nov 24, 2005

### VietDao29

Since you have cos(-x) = cos(x), and $\cos x = \cos (x + 2k \pi) \ \ , k \in \mathbb{Z}$
So the second one is just:
$$- 1.76 + 2 \pi = 4.52$$

7. Nov 24, 2005