Thread: Calculator help

I am trying to graph r^2=2cos(2theta)
in my answer key it's supposed to be an infinity symbol but I get a 4 leaf lemniscate. I am in polar mode so what can be the error?

Originally Posted by aaronb

I am trying to graph r^2=2cos(2theta)
in my answer key it's supposed to be an infinity symbol but I get a 4 leaf lemniscate. I am in polar mode so what can be the error?

If lies between and (or between and ) then is negative and will not have a square root. So the top and bottom leaves of the lemniscate ought not to be there. Maybe you should rewrite the equation as and see what the calculator makes of that version.