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Question
Find the values of:
cos 75°
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Solution
cos 75° = cos(45° + 30°)
= cos 45° cos 30° – sin 45° sin 30°
= `1/sqrt(2)* sqrt(3)/2 - 1/sqrt(2)*1/2`
= `sqrt(3)/(2sqrt(2)) - 1/(2sqrt(2)`
= `(sqrt(3) - 1)/(2sqrt(2)`
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