Initial Value problem. Cant quite get it

[tbomb]

Solve the following Initial Value Problem.

dy/dx=secx^2 - 7sinx, where y(pi/4)=1

I get, y=tanx + 7cosx + C

so, 1=tan(pi/4)+7cos(pi/4) + C

then, C= -7/sqrt(2)

for my final answer, y=tanx+7cosx - 7/sqrt(2)

This answer is wrong, and I dunno where I've messed up.
If someone can critique my calculation it would be a lot of help.

[dirtsniffer]

nvm

[luxor]

Your derivative for sec(x)^2 is not correct.

d/dx[sec(x)^2] = 2tan(x)sec(x)^2

via chain rule

[lumss]

He took the integral, not derivitive.

Looks right to me, you sure you have the question down correct?

[WithTheLightsOn]

Originally posted by luxor
Your derivative for sec(x)^2 is not correct.

d/dx[sec(x)^2] = 2tan(x)sec(x)^2

via chain rule

Yes, but he's suppose to integrate, not differentiate.
BTW, OP your answer should be right, unless you copied the wrong derivative or IV:

http://www.wolframalpha.com/input/?i=dy%2Fdx%3D%28sec%28x%29%29^2+-+7sin%28x%29%2C+y[pi%2F4]+%3D1