1. The problem statement, all variables and given/known data lim x->pi- cot(x) 2. Relevant equations cot(x) = cos(x)/sin(x) 3. The attempt at a solution so substituting pi into: cot(pi) = cos(pi)/sin(pi) = -1/0 so you have a negative over 0, approaching from the -ve side of pi wouldn't it be +infinity? why is it -infinity? additionally this confuses me because a previous question I was working went like: 1)lim x->-3+ (x+2)/(x+3) = - infinity 2)lim x->-3- (x+2)/(x+3) = + infinity when substituting in 3, one would get a -ve int/0. so i thought you found out whether it is +ve or -ve infinity by multiplying signs. 1) -3+ so take + times - (from -ve int) = -ve ...and you get -ve infinity 2) -3- so take - times - (from -ve int) = +ve ...and you get +ve infinity but that was the way a friend showed me, its worked for all the questions up until the cotx one. any help in understanding is much appreciated, thanks.