PreCalc
posted by Emily .
Can you someone please help me with this question??? Simplify cot(x + pi)

you could do this ...
cot(x + pi)
= cos(x+π)/sin(x+π)
= cosx/sinx
= cotx
or
cot(x+π) = 1/tan(x+π) ,
= 1/tanx , since x+π is in quadrant III and according to CAST, in III the tangent is positive.
= cotx