1)tgt/2=sint/(1+cost)
sin2t/(1+cos2t) *cost/(1+cost)=2sintcost*cost/2cos²t(1+cost)=sint/(1+cost)=tgt/2
2)sin2t/(1+cos2t)*cost/(1+cost)*cost/2/(1+cost t/2)=tgt/2*<span>cost/2/(1+cost t/2)=</span>
=sint/2*cost/2/cost/2*(1+cost/2)=sint/2/(1+cost/2)=tgt/4
(4x²-7x+3)-(x²-8x+11)=(4x²-7x+3)+(-x²+8x-11)=
=4x²-7x+3-x²+8x-11=4x²-x²-7x+8x+3-11=3x²+x-8
(9m²-5m+4)-(-10m+m³+5)=(9m²-5m+4+(10m-m³-5)=
=9m²-5m+4+10m-m³-5=-m³+9m²+5m-1