Trig quadrant Question

1. Nov 18, 2006

Destrio

Solve: secx=-5.2, 0≤x≤2π

I'm getting 2 answers:
1.76, 4.52

The answer key is telling me there is only one
1.76

How do I only get 1 answer from this?

Thanks,

2. Nov 18, 2006

Destrio

Evaluate: cot4.47

I'm getting .23 when i plug in: tan(1/4.47)

but the answer key says .25
am I doing something wrong?

thanks

3. Nov 19, 2006

courtrigrad

1. $$\sec x = -5.2, \; 0\leq x\leq 2\pi$$

$$\frac{1}{\cos x} = - 5.2$$

$$\cos x = -\frac{1}{5.2} =$$

$$\arccos(\cos x) = 1.76$$

$$x = 1.76$$

2. $$\cot 4.47 = \frac{1}{\tan 4.47}$$ not $$\tan(\frac{1}{4.47})$$

4. Nov 19, 2006

Destrio

thanks, I see what I did wrong for #2

but, why doesnt #1 have 2 answers?

5. Nov 20, 2006

riddlingminion

Because the second answer is in quadrant 4, where cos is positive.

6. Nov 20, 2006

lotrgreengrapes7926

No, it's in the 3rd quadrant. There should be 2 solutions.

7. Nov 21, 2006

VietDao29

Yes, there should be 2 answers. Cheers. :)

8. Nov 21, 2006

Destrio

Alright
Thanks everyone

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