SOLUTION: Use an Addition or Subtraction Formula to find the exact value of the expression sin(− 11π/12) = Please explain Thanks!

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Question 924578: Use an Addition or Subtraction Formula to find the exact value of the expression
sin(− 11π/12) =
Please explain
Thanks!
Answer by MathLover1(20850) About Me  (Show Source):
You can put this solution on YOUR website!
-11pi%2F12=-%2810pi%2F12%2B1pi%2F12%29=-%285pi%2F6%2B1pi%2F12%29
-5pi%2F6=-150°
-pi%2F6=+-30° =>-1pi%2F12+=-30%2F2=-15°
so, -%285pi%2F6%2B1pi%2F12%29=-150-15=-165°
and sin%28165%29=-0.258819