The secant (theta) takes on values from -1 to -infinity.
So somthing is wrong with the calculator's graph.
Graph your equation by hand.
I have this polar equation to graph and give a value table for. The equation is:
r=1/(1+sec(theta)) or r=1/(1+(1/cos(theta)))
I've done a table for this equation and it doesn't match up with the graph when I put into my calculator. Basically it's giving me negative values when there aren't any negative values on the graph.
Any ideas on what I've done wrong?