Даю 35 баллов. Помогите решить то что сможете.

1 a)sin765=sin(720+45)=sin45=√2/2 b)cos19π/6=cos(3π+π/6)=-cosπ/6=-√3/2 2 cosa=-√(1-sin²a)=-√(1-0,09)=-√0,91 3 1)cosacosb+sinasinb-cosacosb+sinasinb=2sinasinb 2)(-sina-cosa)/(1-2cos²a)=(sina+cosa)/cos2a= =(sina+cosa)/(cosa-sina)(cosa+sina)=1/(cosa-sina) 4 sinxcos3x+cosxsin3x=1 sin(x+3x)=1 sin4x=1 4x=π/2+2πn,n∈z x=π/8+πn/2,n∈z 5 (sina/cosa+cosa/sina)*2sin²2a=(sin²a+cos²a)/sinacosa*2sin²2a= =2/sin2a*2sin²2a=4sin2a 6 a)sinx=1/√2 x=(-1)^n*π/4+πn,n∈z b)tgx/2=√3 x/2=π/3+πn,n∈z x=2π/3+2πn,n∈z 7 cosx/2=1/2 1)x/2=-π/3+2πn,n∈z⇒x=-2π/3+4πn 0≤-2π/3+4πn≤4π 0≤-2+12n≤12 2≤12n≤14 1/6≤n≤7/6 n=1⇒x=-2π/3+4π=10π/3 2)x/2=π/3+2πk,k∈z⇒x=2π/3+4πk,k∈z 0≤2π/3+4πk≤4π 0≤2+12k≤12 -2≤12k≤10 -1/6≤k≤5/6 k=0⇒x=2π/3 8 1)sinx(sinx-1)=0 sinx=0⇒x=πn,n∈z sinx=1⇒x=π/2+2πk,k∈z 2)cosx=a 10a²+3a-1=0 D=9+40=49 a1=(-3-7)/20=-1/2⇒cosx=-1/2⇒x=+-2π/3+2πn,n∈z a2=(-3+7)/20=1/5⇒cosx=1/5⇒x=+-arccos1/5+2πk,k∈z 3)10sinx/2cosx/2+cos²x/2-sin²x/2-5sin²x/2-5cos²x/2=0/cos²x/2 6tg²x/2-10tgx/2+4=0 tgx/2=a 6a²-10a+4=0 D=100-96=4 a1=(10-2)/12=2/3⇒tgx/2=2/3⇒x/2=arctg2/3+πn⇒x=2arctg2/3+πn,n∈z a2=(10+2)/12=1⇒tgx/2=1⇒x/2=π/4+πk,k∈z⇒x=π/2+2πk,k∈z 4)(1-cos2x)²/4+(1+cos2x)²/4=sin²2x 1-2cos2x+cos²2x+1+2cos2x+cos²2x=16sin ²2x 2+2cos²2x=16sin²2x 1+cos²2x-8sin²2x=0 8(1-cos4x)/2-(1+cos4x)/2=1 8-8cos4x-1-cos4x=2 9cos4x=5 cos4x=5/9 4x=+-arccos5/9+2πn,n∈z x=+-1/4*arccos5/9+πn/2,n∈z