Question

value of Sin 330x Cos120+ cos210x sin 300
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Answer 1

Answer:

to evaluate sin 330 × cos 120 + cos 210 sin 300

sin 330 = sin ( 360° - 30°) = - sin 30° = -1/2

cos 120° = cos (180° - 60°) = - cos 60° = - 1/2

cos 210° = cos ( 180° + 30°) = - cos 30° = - √3/2

sin 300° = sin ( 360° - 60°) = - sin 60° = - √3/2

therefore , by substituting these values, we get

=> (-1/2)(-1/2) + (-√3/2)(-√3/2)

=> 1/4 + 3/4

=> 1

sin 330 is - ve as it lies in 4th quadrant

cos 120° is - ve as it lies in 2nd quadrant

cos 210° is - ve as it lies in 3rd quadrant

sin 300° is - ve as it lies in 4th quadrant

sin is + ve in 1st and 2nd quadrant

cos is + ve in 1st and 4th quadrant