Нужна помощь Верно ли равенство: 1) sin 7pi/12 - sin pi/12 = корень 2 / 2 2) cos 11pi/24 - cos pi/8 = -sin 7pi/24 3) sin 11pi/18 + sin 7pi/18=cos 2pi/9 4) cos 5pi/8+cos pi/8=корень 2 *cos 3pi/8

1)sin7π/12-sinπ/12=√2/2 sinπ/12-sinπ/12=√2/2-неверно 2)cos11π/24-cosπ/8=-sin7π/24 -2sin(11π/24+π/8)/2*sin(11π/24+π/8)/1=-2sin14π/48*sin8π/48=-2sin7π/24*sinπ/6= =-2*1/2*sin7π/24 -верно 3)sin11π/18+sin7π/18=cos2π/9 sin11π/18+sin7π/18=2sin(11π/18+7π/18)/2*cos(11π/18-7π/18)/2= =2sinπ*cos4π/18=j -неверно 4)cos5π/8+cosπ/8=√2*cos3π/8 cos5π/8+cosπ/8=2cos(5π/8+π/8)*cos(5π/8-π/8)=2cos3π/4*cosπ/2=0 -неверно