The described angle will be -90° plus any integer multiple of 360°. Possible values for the angle are ...
-90° and 630°
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Angles are conventionally measured counterclockwise from the positive x-axis. The angle shown in the attachment is measured clockwise, so represents a <em>negative</em> 90° angle.
If the solutions are x=-4 and x=3, then it must have factors (x+4)(x-3). Assuming there is no GCF or leading coefficient other than 1, multiply with FOIL to find the standard form.