What is the derivative of this function y= (1+sin x)/(1-sin x)y=1+sinx1sinx?

1 Answer
Nov 5, 2016

dy/dx = ( 2cosx ) / (1-sinx)^2dydx=2cosx(1sinx)2

Explanation:

If you are studying maths, then you should learn the Quotient Rule for Differentiation, and practice how to use it:

d/dx(u/v) = (v(du)/dx-u(dv)/dx)/v^2 ddx(uv)=vdudxudvdxv2, or less formally, (u/v)' = (v(du)-u(dv))/v^2

I was taught to remember the rule in word; " vdu minus udv all over v squared ". To help with the ordering I was taught to remember the acronym, VDU as in Visual Display Unit.

So with y=(1+sinx)/(1-sinx) Then

{ ("Let "u=1+sinx, => , (du)/dx=cosx), ("And "v=1-sinx, =>, (dv)/dx=-cosx ) :}

:. d/dx(u/v) = (v(du)/dx-u(dv)/dx)/v^2
:. dy/dx = ( (1-sinx)(cosx) - (1+sinx)(-cosx) ) / (1-sinx)^2
:. dy/dx = ( cosx-sinxcosx + cosx +sinxcosx ) / (1-sinx)^2
:. dy/dx = ( 2cosx ) / (1-sinx)^2