sina+f(a)=2/3 sina+sin(a+π/2)=2/3sina+sin(-a+π/2)=2/3sina+cosa=2/3 1+2sinacosa=4/9 2sinacosa=-5/9(√2sin(2a-π/4)+1)/(1+tana)=(√2(sin2a√2/2-cos2a√2/2)+1)/(1+tana)=(sin2a-cos2a+1)/(1+tana)=cosa(si...