SOLUTION: Find the exact value using a sum or difference identity. Some simplifications may involve using symmetry and the formulas for negatives. cos (5pi/12)

SOLUTION: Find the exact value using a sum or difference identity. Some simplifications may involve using symmetry and the formulas for negatives. cos (5pi/12)

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Question 1079977: Find the exact value using a sum or difference identity. Some simplifications may involve using symmetry and the formulas for negatives.
cos (5pi/12)
Answer by ikleyn(52788) (Show Source): You can put this solution on YOUR website!
.

 = 75� = 45� + 30� =   =====>

 =   =   ====>


    Use  = ,   = ,   = ,   =   ====>


=  =  = .

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