trig functions

[xc630]

Hello I am having toruble with this problem. It says to give the values of x (in radians) for which cot x is:

a) undefined

b) 0

c) 1

d) -1

Thanks for any help.

 

[Gene]

cot(x)=cos(x)/sin(x)
for 0 < or = x < 2pi
a) when sin(x)=0 which are 0 and pi
b) when cos(x)=0 which are pi/2 and 3pi/2
c) when sin(x)=cos(x) which are pi/4 and 5pi/4
d) when sin(x)=-cos(x) which are 3pi/4 and 7pi/4

Note: b) is a little shakey. cot(x) is also = 1/tan(x) but at x=pi/2 tan(x)=1/0 which is undefined. Maybe one of the other wiser tutors can say if the answers are correct or if they belong in a)