#cos(theta)/(1-tan(theta)) + sin (theta)/ (1-1/tan(theta)) = cos (theta)/(1-(sin(theta)/cos(theta))) + sin (theta)/(1-(cos(theta)/sin(theta)))
= cos^2 (theta) /(cos(theta) -sin (theta)) + sin^2 (theta) /(sin(theta) -cos (theta))
= cos^2 (theta) /(cos(theta) -sin (theta)) - sin^2 (theta) /(cos(theta) -sin (theta))
= (cos^2(theta) -sin^2 (theta)) /((cos(theta) -sin (theta)))
= ((cos (theta) +sin(theta)) cancel( (cos (theta) -sin(theta))))/cancel( (cos(theta) -sin (theta)))
= sin (theta) +cos (theta) #[Proved]