SOLUTION: Use a sum or difference formula to find the exact value of the following. sin(6π/7)cos(3π/28) - cos(6π/7)sin(3π/28) = ?

Algebra ->  Trigonometry-basics -> SOLUTION: Use a sum or difference formula to find the exact value of the following. sin(6π/7)cos(3π/28) - cos(6π/7)sin(3π/28) = ?      Log On


   

Question 984732: Use a sum or difference formula to find the exact value of the following.
sin(6π/7)cos(3π/28) - cos(6π/7)sin(3π/28) = ?
Answer by jim_thompson5910(35256) About Me  (Show Source):
You can put this solution on YOUR website!
sin(6π/7)cos(3π/28) - cos(6π/7)sin(3π/28)

sin(24π/28-3π/28) ... use the identity sin(A-B) = sin(A)cos(B) - cos(A)sin(B)

sin(21π/28)

sin(3π/4)

sqrt(2)/2 ... use the unit circle

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Final Answer: sqrt%282%29%2F2
Note: the '2' in the denominator is NOT inside the square root