What is the value of cos 75°?

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Nov 21, 2015

Answer:

#(sqrt6-sqrt2)/4#

Explanation:

Apply the trig identity: cos (a + b) = cos a.cos b - sin a.sin b
#cos (75) = cos (30 + 45) = cos 30*cos 45 - sin 30*sin 45 =#
= #(sqrt3/2)(sqrt2/2) - (1/2)(sqrt2/2) = (sqrt6-sqrt2)/4#

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