Question | Answer |
angle bisector theorem | If a point is on a bisector of an angle, then it is equidistant from the two sides of the angle |
angle bisector theorem converse | If a point is in the interior of an angle and is equidistant from the sides of an angle, then it lies on the bisector of the angle |
equidistant | the same distance |
perpendicular bisector | a segment, ray, line, or plane that is perpendicular to a segment at its midpoint |
perpendicular bisector theorem | if a point is on the perpendicular bisector of a segment then it is equidistant from the endpoints of the segment |
perpendicular bisector theorem converse | if a point is equidistant from the endpoints of a segment then it is on the perpendicular bisector of the segment |
angle bisector of a triangle | a bisector of an angle of the triangle |
circumcenter of the triangle | the point of concurrency of the perpendicular bisectors of a triangle |
concurrency of angle bisectors of a triangle | the angle bisectors of a triangle intersect at a point that is equidistant from the sides of the triangle |
concurrency of perpendicular bisectors of a triangle | the perpendicular bisectors of a triangle intersect at a point that is equidistant from the vertices of the triangle |
concurrent lines | three or more lines that intersect in the same point |
incenter of the triangle | the point of concurrency of the angle bisectors of a triangle |
perpendicular bisector of a triangle | a line, ray, or segment that is perpendicular to a side of a triangle at the midpoint of the side |
point of concurrency | the point of intersection of concurrent lines |
altitude of a triangle | the perpendicular segment from a vertex of a triangle to the opposite side or to the line that contains the opposite side |
centroid of the triangle | the point of concurrency of the medians of a triangle always inside the triangle |
concurrency of altitudes of a triangle | the lines containing the altitudes of a triangle are concurrent there is always an orthocenter |
concurrency of medians of a triangle | the medians of a triangle intersect at a point that is two thirds of the distance from each vertex to the midpoint of the opposite side |
median of a triangle | a segment whose endpoints are a vertex of the triangle and the midpoint of the opposite side |
orthocenter of a triangle | the point of concurrency of the lines containing the altitudes of a triangle |
midsegment of a triangle | a segment that connects the midpoints of two sides of a triangle |
midsegment theorem | the segment connecting the midpoints of two sides of a triangle is parallel to the third side and is half as long |
exterior angle inequality theorem | the measure of an exterior angle of a triangle greater than the measure of either of the two nonadjacent interior angles |
| if one side of a triangle is longer than another side then the angle opposite the longer side is larger than the angle opposite the shorter side |
| if one angle of a triangle is larger than another angle then the side opposite the larger angle is longer than the side opposite the smaller angle |
triangle inequality theorem | the sum of the lengths of any two sides of a triangle is greater than the length of the third side |
hinge theorem | if two sides of one triangle are congruent to two sides of another triangle and the included angle of the first is larger than the included angle of the second then the third side of the first is longer than the third side of the second |
hinge theorem converse | if two sides of one triangle are congruent to two sides of another triangle and the third side of the first is longe rthan the third side of the second then the included angle of the first is larger than the included angle of the second |