Jawabanmu

2014-06-16T18:24:05+07:00
Sin 240° + sin 225° + cos 315°
= sin (270-30)° + sin (270-45)° + cos (360-45)°
= -cos 30° + (-cos 45°) + cos 45°
= - 1/2 √3 - 1/2 √2 + 1/2 √2
= - 1/2 √3