∓

Description
The plus sign placed below the minus sign, as an inverse of.

Symbol

 * 1)  The minus-plus sign: used after ± to indicate that when the first operation is 'plus', this one is 'minus', and vice versa.
 * $$\cos(x \pm y) = \cos x \cos y \mp \sin x \sin y \iff \big(\cos(x + y) = \cos x \cos y - \sin x \sin y \wedge \cos(x - y) = \cos x \cos y + \sin x \sin y\big)$$
 * 1)  Advantage for black.
 * 2)  A tredecile (3⁄10) aspect of 108°.