# Trig function help

thanks

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Can you give the entire problem?

Can you give the entire problem?

all thats given is that

What is the question? What are you asked to find?

What is the question? What are you asked to find?
what is =cos2x

What is x supposed to be? Is the given problem in terms of t? Are you trying to solve for t and then plug that value in for x?

its basically asking you to use the double angle formula
but im not sure how to find those values

If you're simply trying to find t, then use cot = 1/tan... If you have a value for t why do you need to use the double angle identities?

to find what cos2t is ....

you can find what tan is from cot
then i drew a triangle and got the hypot to be sqrt(41)

but how do i do that math

formula for cos2t = cos^2(t) - sin^2(t)

Are you forbidden from using a calculator?

Are you forbidden from using a calculator?

teacher said u can use it
but need to know how to do it without one for test

Well that may have been useful information at the start...

you have cot = -5/4, find what tan is then recall tan = sin/cos ... or recall cot = cos/sin...

well i worked it out and i believe i got the answer to be 9/41

That's what I'm getting