sec theta = undefined
We know that sec = 1 /cos
1/ ( cos theta) = undefined
We need to find where the cos theta = 0
Looking for where the x coordinate of the ordered pair is zero
( 0,1) occurs on the y axis so when theta = 90 degrees
(0, -1) also occurs at the bottom of the y axis so theta = 270 degrees
sec theta = undefined when theta = 90 or 270 degrees
