Find the value of sin 660 degree + sin 780 degrees
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Answer:
sin 780° = sin 60° = √3/2
sin 660° = 300° = -√3/2
sin 420° = 60° = √3/2
sin 780 - sin 660 - sin 420 + sin 60
= √3/2 - (-√3/2) - √3/2 +√3/2
= 0
Answered by
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Answer:
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Step-by-step explanation:
sin 660° = sin (660° - 360° - 360°)
= sin (-60°) (IV quadrant where sin and sec will be negative)
(sin 60° = √3/2)
= - √3/2
sin 780° = sin (780°-360°-360°)
= sin 60° (Lies in the I quadrant where sin is positive)
= √3/2
Hence sin660° +sin 780° = (-√3/2)+(√3/2)
= 0
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