1. tga*ctg-cos^2a=

2. sin^3a+sina*cos^2a/tga=

3. sin^2a+2cos^2a-1=

4.3sin0+2cos0=

5.1+tg (3 pi/2+a) * sina*cosa=

1) tga*ctg-cos^2 a = 1-сos^2 a = sin^2 a

2) sin^3 a+sina*cos^2 a/tga = sin^3 a+sina*cos^2 a / (sina/cosa) = sin^3 a+cos^3 a

3) sin^2 a+2cos^2 a-1 = sin^2 a+2cos^2 a-sin^2 a-cos^2 a = cos^2 a

4) 3sin0+2cos0 = 3*0+2*1 = 0+2 = 2

5) 1+tg (3 pi/2+a) * sina*cosa = 1-ctga*sina*cosa = 1-cos^2 a = sin^2 a