Question

найдите значение выражения cos53*cos7-cos37×sin7/sin74cos44-cos74*cos46

Answer 1

cos(a+b)=coaacosb-sinasinb
cos53cos7-cos(90-37)sin7=cos53cos7-sin53sin7=cos60
sin(a-b)=sinacosb-cosasinb
sin74cos44-cos74cos(90-46)=sin74cos44-cos74sin44=sin(74-44)=sin30
Cos60/sin30=1