- #1
shocklightnin
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Homework Statement
lim x->pi- cot(x)
Homework Equations
cot(x) = cos(x)/sin(x)
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.