How do you use the limit definition to find the derivative of y = cscxy=cscx?

1 Answer
Dec 2, 2016

The key parts are in the explanation section, below.

Explanation:

(1/sin(x+h)-1/sinx)/h = (sinx-sin(x+h))/(hsin(x+h)sinx)1sin(x+h)1sinxh=sinxsin(x+h)hsin(x+h)sinx

= (sinx-sinxcos h-cosxsin h)/(hsin(x+h)sinx)=sinxsinxcoshcosxsinhhsin(x+h)sinx

= (sinx(1-cos h)/h - cosxsin h/h)*1/(sin(x+h)sinx)=(sinx1coshhcosxsinhh)1sin(x+h)sinx

Taking the limit gets us

(-cosx)/sin^2 x = -cscxcotxcosxsin2x=cscxcotx