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Related to interior angle: exterior angle
1. an angle of a polygon contained between two adjacent sides
2. any of the four angles made by a transversal that lie inside the region between the two intersected lines
interior angle[in′tir·ē·ər ′aŋ·gəl]
An angle between two adjacent sides of a polygon that lies within the polygon.
For a line (called the transversal) that intersects two other lines, an angle between the transversal and one of the two lines that lies within the space between the two lines.