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### Given that d/dx(cosx)=-sinx show that d/dx(secx)=secx(tanx)

let y=sec(x) = 1/(cos(X)) = cos(x)-1

Thus dy/dx = -1(cos(x))-2(-sinx) = sin(x)/(cos(x))2

= 1/cos(x)  x  sin(x)/cos(x)

=sec(x)tan(x)

8 months ago

Answered by Owain, who has applied to tutor A Level Maths with MyTutor

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