Question

cos420°+sin(-390°) помогите

Answer 1

Ответ:

0

Объяснение:

cos(420°)+sin(-390°)=cos(360°+60°)+sin(-360°-30°)=cos(60°)+sin(-30°)=

=cos(60°)-sin(30°)=0,5-0,5=0

Answer 2

$Cos420^{o}+Sin(- 390^{o} ) = Cos(360^{o}+ 60^{o} )- Sin(360^{o}+30^{o}) =\\= Cos60^{o}-Sin30^{0}=\frac{1}{2}-\frac{1}{2}=0$