Question

sin87-sin59-sin93+sin61=sin1 проверить равенство

Answer 1

sin87°-sin59°-sin93°+sin61°=sin87°-sin93+(sin61-sin59°)= 
=sin(90-3)°-sin(90+3)+2*sin1°*cos60°=cos3°-cos3+2*sin1°*cos60°=2*1/2*sin1°=sin1°