The equation y = 7 cos [pi/3 t] models the height h in centimeters after t seconds of a weight attached to the end of a spring that has been stretched and then released. a. Solve the equation for t. b. Find the times at which the weight is first at a height of 1 cm, of 3 cm, and of 5 cm above the rest position. Round your answers to the nearest hundredth. c. Find the times at which the weight is at a height of 1 cm, of 3 cm, and of 5 cm below the rest position for the second time. Round your answers to the nearest hundredth.

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anonymous · Answer

This is another one I'm stock on... hard for me in any case but not I'm betting a migrane.. I'll so glad this is my lass course... it might take me awhile... but I can't fail now

anonymous · Answer

opps stuck on that is

anonymous · Answer

and I meant I am betting a migrane, lol not not getting one

anonymous · Answer

Thanks again for your help !!

anonymous · Answer

It's not that hard. Just get the cos of (whatever you have--in this case pi/3t) by itself like this:
|dw:1342770644881:dw|

We want to get to the t, and now that the cos of whatever is by itself, we are able to work with it because we can't do anything with the t until it is out of control of the cos.
What you need to do is the inverse cosine to both sides, just like when you divided the 7. Think of it like diving both sides by a cosine:
|dw:1342770859635:dw|
Now that the t is out of the control of cosine, just multiply both sides by 3t, then divide both sides by 3 cos-1(y/7) to get an equation where you have:
t=answer