Решить плз забыл 1)sinxsin3x+sin4xsin8x=0 2)cos3xsin7x=cos2xsin8x 3)sin5xcos3x=sin2xcos6x

1)1/2(cos(x-3x)-cos(x+3x))+ 1/2(cos(4x-8x)-cos(4x+12x))=0 1/2(cos2x-cos4x+cos4x-cos12x)=0 1/2(cos2x-cos12x)=0 -2sin(2x+12x)/2•sin(2x-12x)/2=0 sin7x•sin5x•(-2•(-1))=0 sin7x=0 7x=πn x=πn/7 sin5x=0 5x=πn x=πn/5 ответ πn/5; πn/7 n€z

lim х→1 ((x^2-1)/(1-x)= lim х→1 ((x-1)(x+1))/(1-x)=

lim х→1 ( - (1-x)(x+1))/(1-x) = lim х→1 (- (x + 1)) = -2