Related Rates (kite) fall 2012

A related rates problem about a kite!

[hunterrjohnson]

You mean sin(pi/12)? as the final answer for theta prime? I get -.02 and there can only be one right answer. How do your steps differ from mine?

[aldrindarrenbonayon]

I think it makes more difficult. Is it necessary to convert the deg to rad? like what you did to the vid ?
But however i got it -0.02 rad/sec also. I used sec^2 (theta) = 1/cos^2 (theta) Then, cos^2 (theta) = x^2/200^2 = 3/4
1 / 3/4 ; sec^2 (theta) = 4/3

Final formula : -100(dx/dt) / x^2 (sec^2(theta))
: -100(dx/dt) / x^2 (4/3)
: -3(100)(8) / (30000)"note: from pythagorean to get x." (4)
: -0.02rad/sec

[rudreshramnarain]

Would sin .5 (pi/6 ) be acceptable? That was my initial answer..

[lilianahaus]

How do you know to use tan(theta) = 100/x rather than cos(theta) = x/z?

[ZachBrannigan]

I needed help with a question from the textbook, went to the internet to find help, found it was the exact same question...
Whoops.

[hunterrjohnson]

It sounds like you found the instantaneous value of theta, when the string is 200 ft long, which you do need eventually. But to solve for theta' you have to differentiate first.

[jumboXJ]

I think you forgot to square the 30000 at the end

[Legendofmudkip]

Thank you for this video, it was very helpful :)

[rudreshramnarain]

I used sin = opposite/ Hypotenuse which is sin (100/200) or pi/6 in this case. I think I didn't finish the problem. I didn't differentiate.