What function is y = cos(x +π) equal to

can you also explain the answer

thanks

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- Sep 23rd 2012, 07:14 AMubhuttoHelp with Cosine Function
What function is y = cos(x +

**π**) equal to

can you also explain the answer

thanks - Sep 23rd 2012, 07:32 AMMarkFLRe: Help with Cosine Function
Use the angle-sum identity for cosine:

You may also think of the unit circle. Pick an arbitrary point on the circle. The counter-clockwise angle to the radius at this point as measured from the positive*x*-axis is the angle . The*x*-coordinate of this point is . To add radians to this angle, go to the point on the opposite side of the circle, on the other end of the diameter. Can you see what relation the new*x*-coordinate will always have with the original? - Sep 23rd 2012, 07:43 AMSworDRe: Help with Cosine Function

Whenever you add to the input you shift it to the left by Pi/2, so when you add Pi, you do that twice, so you effectively move from cos to -cos. So