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C3 differentiation help please

Given that y=secx+tanx, find dy/dx and show that it can be written in the form 1/1-sinx

My working out:

dy/dx = secxtanx+sec2x

then I converted them
= 1/cosx ( sec2x -1 ) + 1/cos2x

Am I on the right track? If not please help mee!
:tongue:
Reply 1
Original post by queenfatso
Given that y=secx+tanx, find dy/dx and show that it can be written in the form 1/1-sinx

My working out:

dy/dx = secxtanx+sec2x

then I converted them
= 1/cosx ( sec2x -1 ) + 1/cos2x

Am I on the right track? If not please help mee!
:tongue:


Write the whole thing as one fraction: dydx=sec(x)tan(x)+sec2(x)=sin(x)+1cos2(x) \displaystyle \frac{dy}{dx} = \sec(x)\tan(x) + \sec^2(x) = \frac{\sin(x)+1}{\cos^2(x)} . Rewrite the denominator in terms of a familiar identity and then think about difference of two squares.

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