SUPPLEMENT

SUPPLEMENT, OF AN ARCH OR ANGLE, in geometry or trigonometry, is what it wants of a semicircle, or of $180^\backslash circ$; as the complement is what it wants of a quadrant, or of $90^\backslash circ$. So, the supplement of $30^\backslash circ$ is $130^\backslash circ$; as the complement of it is $40^\backslash circ$.