When I graph a polar equation on a TI-89, I get an error saying "undefined variable." What should I do?

Question

This only happens when I have r^2= something. For instance: r^2=cos(2theta)

Answer 1

Define the variable

Answer 2

i've got on no account achieved the excellent operation which you're stating, yet while i'm doing new (and complex) apps on my TI-89, I continually sparkling a-z first... turn 89 on, visit abode, then press F1, then scroll over to F6 making use of the arrow keys (correct arrow), at F6-press enter, then enter back. this would sparkling any archives saved to any variables from previous apps that is getting interior the way. i do no longer understand that this would restore your challenge, whether it is well worth a shot. good success. Oh yeah, when you are trying this, you will would desire to thoroughly reenter what you're attempting to do back.