Term | Definition |
equilateral triangle | a triangle whose three sides are equal in length |
isosceles triangle | a triangle with two sides that are equal in length |
scalene triangle | a triangle whose three sides are all different in length |
acute triangle | a triangle whose 3 angles are all less than 90 degrees |
equiangular triangle | a triangle whose 3 angles are equal |
right triangle | a triangle with one angle of 90 degrees |
obtuse triangle | a triangle with an angle of more than 90 degrees |
hypotenuse | the side opposite the right angle in a right triangle |
base of an isosceles triangle | the side of an isosceles triangle that is not the legs (the two sides that are congruent) |
base angles of an isosceles triangle | the two congruent angles on an isosceles triangle |
corollary | a theorem that follows from another theorem |
perpendicular bisector of a triangle | a perpendicular line through the midpoint of a side of the triangle |
angle bisector of a triangle | a line that divides an angle of the triangle into two congruent parts |
point of concurrency | the point where three or more lines intersect |
concurrent lines | when three or more lines intersect in the same point |
circumcenter of a triangle | the point of concurrency of the perpendicular bisectors of a triangle |
incenter of a triangle | the point of concurrency of the angle bisectors |
median of a triangle | a segment whose endpoints are a vertex of the triangle and the midpoint of the opposite side |
centroid of a triangle | the point of concurrency of the three medians of a triangle |
altitude of a triangle | the perpendicular segment from a vertex to the opposite side or to the line that contains the opposite side |
orthocenter of a triangle | the point of concurrency of the three altitude lines |
mid segment of a triangle | a segment that connects the midpoints of two sides of a triangle |
vertex angle of an isosceles triangle | the angle that is not congruent to the others in an isosceles triangle |