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