Question

алгебра 123456789123456789

Answer 1

tga=3
cos²a=1:(1+tg²a)=1:(1+9)=1/10
cosa=1/√10
sina=√(1-cos²a)=√(1-1/10)=3/√10
sin2a=2sinacosa=2*3/√10*1/√10=3/5
cos2a=2cos²a-1=1/5-1=-4/5
(2sin2a-3cos2a)/(4sin2a+5cos2a)=(6/5+12/5):(12/5-20/5)=
=18/5*(-5/8)=-2,25