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## gjhfdfg Group Title Use a graphing calculator to solve the equation -3 cos t = 1 in the interval from 0 to 2p. Round to the nearest hundredth. 2 years ago 2 years ago

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1. gjhfdfg

I typed it in on my calculator but did not do a thingg!

2. swissgirl

$$\cos(t)=\large{1 \over- 3}$$ $$\cos^{-1}(\large{1 \over- 3} )=t$$

3. gjhfdfg

How did you get that?

4. swissgirl

First I divided -3 from both sides

5. swissgirl

$$-3\cos(t)=1$$ $$\large {-3\cos(t) \over -3}={1 \over -3}$$ $$\cos(t)=\large{1 \over -3}$$ $$\cos^{-1}(\cos(t))=Cos^{-1}(\large{1 \over -3})$$ $$t=Cos^{-1}(\large{1 \over -3})$$

6. gjhfdfg

How would you put this in a decimal form.?

7. swissgirl

lol you gotta put this into your calc first and then your answer will be a decimal

8. gjhfdfg

Oh wow that was dumb of me lol. I was thinking this had to be put in a decimal form.! before solving it

9. gjhfdfg

I got 109.47

10. swissgirl

Are you supossed to be working in radians or degrees?

11. gjhfdfg

Ah, I had my calc set in degrees, I'm pretty sure I'm suppose to be using radians.! Gah I keep forgetting to change the mode

12. gjhfdfg

Ok now I got 1.91.!

13. swissgirl

YUP THAT IS WHAT I GOT :)

14. gjhfdfg

Thanks for the help.! (-: