31/2*(1+cos(4x-π/2))+1/2*(1+cos(5x+π/2)=11+sin4x+1-sin5x=2sin4x-sin5x=02sin(-x/2)cos(9x/2)=0sin(-x/2)=0x/2=πn.n∈zx=360n,n∈z0≤360n≤1800≤n≤0,5нет решения на промежутке [0;180]cos(9x/2)=09x/2=π/2+πk,k∈zx=20+40k,k∈z0≤20+40k≤180-20≤40k≤160-0,5≤k≤4k=0⇒x1=20k=1⇒x2=60k=2⇒x3=100k=3⇒x4=140k=4⇒x5=180x1+x2+x3+x4+x5=20+60+100+140+180=50041/2*(1-cos(4x-π/2))=1/2(sin(5x/2+π/4-5x/2-7π/4)+sin(5x/2+π/4+5x/2+7π/4))1-sin4x=sin(-3π/2)+sin(5x+2π)1-sin4x=1+sin5xsin5x+sin4x=02sin(9x/2)cos(x/2)=0sin(9x/2)=09x/2=πn,n∈zx=2πn/9,n∈zcos(x/2)=0x/2=π/2+πk,k∈zx=π+2πk,k∈z