Albert wants to show that tan(theta)sin(theta)+cos(theta)=sec (theta). he writes the following proof: tan(theta)sin(theta)+cos(theta)=sec (theta) sin(theta)/cos(theta) sin(theta)+cos(theta)=sec(theta) sin^2(theta)/cos(theta)+cos(theta)= sec(theta) what is the next step in this proof? a.) he should write tan(theta)=sin(theta)/cos(theta) to find a common denominator. b.) he should write cos(theta)=cos^2(theta)/cos(theta) to find a common denominator. c.) he should write cos(theta)=1-sin(theta) to convert all the terms to sine. d.) he should write sin(theta)=1-cos(theta) to convert all the terms to cosine.