НЕВЕРОЯТНО МНОГО БАЛЛОВ! Задания(слева от вас, т.е. 1-й вариант). 1 - а, 1 - б. 2 - ну, вот это тождество. 3 - а.

2cos²(18π+5π)/24cos²(18π-5π)/24=(2cos(18π/12+5π/12)/2cos(18π/12-5π/12)/2)*0.5(2cos(18π/12+5π/12)/2cos(18π/12-5π/12)/2)= (cos18π/12+cos5π/12)*0.5(cos18π/12+cos5π/12)=0.5(cos18π/12+cos5π/12)²=0.5(cos(π+π/2)+ 2)cos68cos22-sin3sin87+sin25cos20.5=cos(90-22)cos22-sin3sin(90-3)+sin25cos20.5=sin22cos22-sin3cos3+sin25cos20.5=0.5sin44+0.5sin6-sin25cos20.5=0.5·2sin25cos38-sin25cos20.5=sin25(cos38+cos20.5)=sin25(2cos58.5/2cos17.5/2 (sin34cos16-sin(90-34)sin16)/(sin(90-82)+cos82cos10)= (sin34cos16-cos34sin16)/(cos82+cos82cos10)= sin(34-16)/cos82(1+cos10)=sin18/cos82(1+cos10) здесь явно описка 3)a  (1+sin2α)/(1-sin2α)*cos²(π/4+α)/sin²(π/4+α)=(1+sin2α)/(1-sin2α)/(1+cos2(π/4+α))/(1-cos2(π/4+α))=(1+sin2α)/(1-sin2α)*(1+cos(π/2+2α)/(1-cos(π/2+α)=(1+sin2α)/(1-sin2α)*(1-sin2α)/(1+sin2α)=1