The exterior angle of a polygon and its corresponding interior angle always add up to 180°.
Let the interior angle of the polygon be [tex] y^{\circ} [/tex]
[tex] 45^{\circ}+y=180^{\circ} [/tex]
So, [tex] y=180^{\circ}-45^{\circ} [/tex]
[tex] y=135^{\circ} [/tex]
So, the interior angle of the polygon is [tex] 135^{\circ} [/tex]
