Question

Помогите
$5(cos 430 * sin 400 - sin 130 cos740)$

Answer 1

5(cos430sin400-sin130cos740)=
=5(cos(360+70)sin(360+40)-sin(180-50)cos(720+20))=
=5(cos70sin40-sin50cos20)=
=5(cos(90-20)sin(90-50)-sin50cos20)=
=5(sin20cos50-sin50cos20)=
=5(sin(20-50))=
=5(sin(-30))=
=-5sin30=
=-5*1/2=
=-2,5