Question

cos3x=0.5 и...cos3x=+-1/2

Answer 1

sin3x*cos5x-sin5x*cos3x=0,5

sin(3x-5x)=1/2

sin2x=-1/2

2x=-П/6+2Пk x=-П/12+Пk

2x=-5П/6+2Пk x=-5П/12+Пk