What does 3<180 mean in the polynomial calculator mode?

Looks like complex number mod-arg form so its really -3 which is a root of the quadratic

What does this mean? Its the first time I've never seen it.
This is used for 2x^2+5x-3=0

@mqb2766 is correct. It is a quirk of the Casio fx-991EX that if the complex mode of the calculator is set to the r, theta option, it will present negative real roots in this form. The angle symbol at the top of the calculator display conforms that the complex mode is set to r, theta. To revert to a more conventional presentation of negative real roots, you need to go into the menu and set the complex mode to "a + bi". The complex setting is on the second page of menu options after keying shift-menu.

@mqb2766 is correct. It is a quirk of the Casio fx-991EX that if the complex mode of the calculator is set to the r, theta option, it will present negative real roots in this form. The angle symbol at the top of the calculator display conforms that the complex mode is set to r, theta. To revert to a more conventional presentation of negative real roots, you need to go into the menu and set the complex mode to "a + bi". The complex setting is on the second page of menu options after keying shift-menu.