Question

Express as a sum of diffrence of two trignometric function 2 cos 75° cos 35°

Answer 1

Step-by-step explanation:

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we know that

cosc + cosd = 2cos(c+d/2)cos(c-d/2)

so,

c=110°

d=40°

Thus, your answer becomes,

cos(110°)+cos(40°)