SOLUTION: Find the exact value of sin 225 degrees. You must use a sum or difference formula for your solution to be graded

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Question 981306: Find the exact value of sin 225 degrees. You must use a sum or difference formula for your solution to be graded
Answer by MathLover1(20850) About Me  (Show Source):
You can put this solution on YOUR website!
first write sin+%28225%29 as sin+%28180%2B45+%29+
then we have sin%28180%2B45%29
use a sum formula

sin%28180%2B45%29+=+sin%28180%29cos%2845%29+%2B+cos%28180%29sin%2845%29....since sin%28180%29=0,sin%2845%29=1%2Fsqrt%282%29,cos%2845%29=1%2Fsqrt%282%29, and cos%28180%29=-1, we have
sin%28180%2B45+%29+=+0%2A%281%2Fsqrt%282%29%29+%2B%28-1%29%281%2Fsqrt%282%29%29
sin%28180%2B45+%29+=+-1%2Fsqrt%282%29