Geometry Glossary - I

 

Incenter:

the center of the inscribed circle in a triangle; in the illustration shown below, point P is the incenter

 

Included angle:

the angle formed by two consecutive sides of a triangle (or polygon)

Inscribed angle:

an angle whose vertex lies on the circle and whose sides contain chords of the circle

Inscribed circle:

a circle about which a polygon is circumscribed

Intercepted arc:

an angle intercepts an arc if and only if the endpoints of the arc lie on the circle and all points on the arc, except its endpoints, are in the interior of the angle

Intersection:

the points common to two or more figures

Intersecting lines:

lines in the same plane intersect in exactly one point, unless they are parallel

Isosceles triangle:

a triangle with at least two sides congruent