Tga=2
cos²a=1:(1+tg²a)=1:(1+4)=1/5
cosa=1/√5
sin²a=1-cos²a=1-1/5=4/5
sina=2/√5
ctga=1/2
ctg²=1/4
2
(2sin²a-sinacosa)/(3sin²a+2cos²a)=(8/5-2/5):(12/5+2/5)=6/5:14/5=
=6/5*5/14=6/14=3/7
4
(sina+3cosa)/(sina-cosa)ctg²a=(2/√5+3/√5):[(2/√5-1/√5)*1/4]=
=5/√5:1/4√5=5/√5*4√5=20