Question

sin 17 -sin35 решение

Answer 1

$sin(17)-sin(35) = 2cos( frac{17+35}{2} )sin( frac{17-35}{2} ) = 2cos( frac{52}{2})sin(- frac{18}{2} )= \ = 2cos(26)sin(-9) = - 2cos(26)sin(9)$