#sin(theta) - csc(theta) + sec(theta)#
#=sin(theta)- 1/sin(theta) +1/cos(theta)#
#=(sin(theta)sin(theta)-1)/sin(theta) + 1/cos(theta)#
#=(sin^2(theta)-1)/sin(theta) + 1/cos(theta)#
#=-(1-sin^2(theta))/sin(theta) + 1/cos(theta)#
#=-cos^2(theta)/sin(theta) +1/cos(theta)#
#=(-cos^2(theta)*cos(theta))+1/(sin(theta)cos(theta))#
#=(-cos^3(theta)+1)/(cos(theta)sqrt(1-cos^2(theta))#
#=(1-cos^3(theta))/(cos(theta)sqrt(1-cos^2(theta))#