Simplify. cos^2[(pi/2) - x] + cos^2[(pi/2) - x] + cos^2x

Numerator
cos(π/2−x)=cos(π/2)cosx+sin(π/2)sinx
now cos(π/2)=0 and sin(π/2)=1
simplifies to : 0 + sinx = sinx
Denominator
sin(π/2−x)=sin(π/2)cosx+cos(π/2)sinx
simplifies to : cosx + 0 = cosx
⇒cos(π/2−x)sin(π/2−x)=sinx/cosx=tanx