tan^2x(1+1/tan^2x)=1/cos^2x tan^2x+(tan^x/tan^2x)=1/cos^2x tan^2x+1=1/cos^2x sin^2x/cos^2x+1=1/cos^2x (sin^x+cos^2)/cos^2x=1/cos^2x 1/cos^2x=1/cos^2x
You can ask a new question or answer this question.