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Question
Find the value of sin 75°.
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 xx sqrt3/2 + 1/sqrt2 xx 1/2`
`= (sqrt3 + 1)/(2sqrt2) xx sqrt2/sqrt2`
`= (sqrt6 + sqrt2)/4`
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