Published by admin on September 15, 2020 Use the following facts: ##tanx=sinx/cosx## ##sin2x=2sinxcosx## ##cos2x=cos^2x-sin^2x## ##sin^2x+cos^2x=1## So you get: ##(1-sinx/cosx)/(1+sinx/cosx)=(1-2sinxcosx)/(cos^2x-sin^2x)## ##(cosx-sinx)/cancel(cosx)*cancel((cosx))/cancel((cosx+sinx))=(1-2sinxcosx)/((cosx-sinx)cancel((cosx+sinx)))## Taking: ##(cosx-sinx)## to the left side and using the fact that: ##sin^2x+cos^2x=1## ##(cosx-sinx)^2=sin^2x+cos^2x-2sinxcosx## […]