Question

2cos80° + 4sen70°sen10°

Answer 1

cos80=cos(70+10) = cos70.cos10 - sen70.sen10

reemplazando:

2cos70.cos10 -2sen70.sen10 + 4sen70.sen10

= 2cos70.cos10 + 2sen70.sen10

=2(cos70.cos10 + sen70.sen10)

= 2 (cos(70 - 10))

= 2 cos60

= 2(1/2)

= 2/2

=1