If I am using the addition and subtraction formula, how would I simplify cos(x + [pi])?
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Originally Posted by mike1 If I am using the addition and subtraction formula, how would I simplify cos(x + [pi])? cos(A + B) = cos(A)cos(B) - sin(A)sin(B) So cos(x + [pi]) = cos(x)cos([pi]) - sin(x)sin([pi]) cos([pi]) = -1 sin([pi]) = 0 Thus cos(x + [pi]) = -cos(x) -Dan
That helps, thanks alot.
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