Упростите:1+cosa+cos2a+cps3a/cosa+2cos^2a-1

Question

Упростите:1+cosa+cos2a+cps3a/cosa+2cos^2a-1

Answer 1

[(1+cos2a)+2cos2acosa]/(cosa+cos2a)=(2cos²a+2cos2acosa)/(cosa+cos2a)=
=2cosa(cosa+cos2a)/(cosa+cos2a)=2cosa