SOLUTION: Use an Addition or Subtraction Formula to find the exact value of the expression. cos 195°

Algebra ->  Trigonometry-basics -> SOLUTION: Use an Addition or Subtraction Formula to find the exact value of the expression. cos 195°      Log On


   

Question 873030: Use an Addition or Subtraction Formula to find the exact value of the expression.
cos 195°
Answer by stanbon(75887) About Me  (Show Source):
You can put this solution on YOUR website!
Use an Addition or Subtraction Formula to find the exact value of the expression.
cos 195°
----------------
cos(195) = -cos(15) = -cos(30/2)
Use the half-angle formula to solve.
Cheers,
Stan H.
----------------------