1) sin 240° + cos (-210°)

2) sin 330° + cos (-300°)

1) sin 240 + cos (-210) = sin 240 - cos 210 = sin (180 + 60) - cos (180 + 30) =

= - sin 60 + cos 30 = - sgrt3/2 + sgrt3/2 = 0;

2) sin 330 + cos (-300) = sin (360 - 30) + cos (-360 + 60) = sin (-30) + cos 60 =

= - sin 30 + cos 60 = - 1/2 + 1/2 = 0.

1) sin240⁰+cos (-210⁰) = sin (270⁰-30⁰) + cos210⁰=-cos30°+cos (270°-60°) = - √3/2-sin60°=-√3/0-√3/2=-√3

2) sin330°+cos (-300°) = sin (270°+60°) + cos300°=-cos60°+cos (270°+30°) = - cos60°+sin30°=-0.5+0.5=0