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OCR mei pure mathematics C4 help for june'11 exam!

im currently revising for C4 and i am revising parametrci equations.. and im using the MEI structured mathematics edition 3 book to revise. and i am stuck on one question on page 242 Q.2.

it is asking to differentiate x=tanx and y= tan2x


and to find the value of dy/dx when x= (pie)/6..i.e 30 degrees.

the answer is 6 on the back of the book but i have no idea how to do it!
can anyone help?
Reply 1
Avatar for vc94
vc94
12
If it's parametric then I think you mean: x=tant and y= tan2t

dy/dx is given by (dy/dt)/(dx/dt)

You then substitute t=pi/6 to get the gradient.
Reply 2
Avatar for .matt
.matt
1
I'm guessing it's x=tan(t), y=tan(2t)? If you're not sure how to differentiate tan, use the quotient rule on tan(t) = cos(t)/sin(t)
Reply 3
Avatar for angie92
angie92
OP
In the book the question is x= tan0 as in feta if you get me, and y= tan20 so i meant x to be equivalent to feta, i.e the degree.
it doesnt say x=tan2t
Reply 4
Avatar for angie92
angie92
OP
my problem with the question is that i didnt know how to divide the (dx/dt)/(dy/dt)

for dx/dt i got.. sec^2(t)

and for dy/dt i got 2sec^2(2t)

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