| A | B |
|---|
| right triangle | a triangle with exactly one 90 degree angle |
| acute triangle | a triangle with three angles less than 90 degrees |
| obtuse triangle | a triangle with exactly one angle greater than 90 degrees |
| scalene triangle | a triangle with three sides of different lengths |
| isosceles triangle | a triangle with at least two sides the same length |
| vertex angle | the angle between the two sides of equal length in an isosceles triangle |
| base | the side opposite the vertex angle in an isosceles triangle |
| base angles | the two angles opposite the two sides of equal length in an isosceles triangle |
| equilateral triangle | a triangle with three sides of equal length |
| median of a triangle | a segment connecting the midpoint of a side to the opposite side |
| altitude of a triangle | a perpendicular segment from a vertex to the opposite side or a line containing the opposite side |
| height of a triangle | the length of the altitude |
| trapezoid | a quadrilateral with one pair of parallel sides |
| parallelogram | a quadrilateral with two paors of parallel sides, opposite angles are equal and opposited sides are equal |
| rhombus | a parallelogram with four equal sides |
| rectangle | a parallelogram with four 90 degree angles |
| square | a parallelogram with four equal sides and four 90 degree angles |
