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Question
Find the value of: sin 75°
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Solution
sin (75°) = sin (45° + 30°)
= sin 45° cos 30° + cos 45° sin 30°
[∵ sin (A + B) = sin A cos B + cos A sin B]
= `(1/sqrt2) (sqrt3/2)+ (1/sqrt2), (1/2)`
[∵ sin 45° = `1/sqrt2,cos 30°= sqrt3/2, sin 30° = 1/2`]
= `(sqrt3+1)/(2sqrt2)`
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