| A | B |
|---|
| midsegment | joins midpoints of two sides of a triangle |
| coordinate proof | figure drawn on a coordinate plane and the formulas for slope, midpoint, and distance are used to prove properties of the figure |
| distance from point to line | length of the perpendicular segment from the point to the line |
| concurrent lines | three or more lines that meet in one point |
| point of concurrency | point at which concurrent lines intersect |
| circumcenter of a triangle | point of concurrency of the perpendicular bisectors of a triangle |
| circumscribed about | vertices of polygon are on the triangle |
| incenter of a triangle | point of concurrency of the angle bisectors of the triangle |
| inscribed in | sides of polygon are tangent to the circle |
| median of a triangle | segment with endpoints at a vertex of triangle and midpoint of opposite side |
| centroid | point of intersection of the medians of triangle (point of balance) |
| altitude of a triangle | perpendicular segment from a vertex to line containing side opposite of that vertex |
| orthocenter of a triangle | point of concurrency of altitudes of the triangle |
| negation | has the opposite meaning of the original statement |
| inverse | "if p, then q" is the conditional, "if not p, then not q" |
| contrapositive | "if p, then q" is the conditional, "if not q, then not p." Always has same truth value as its conditional. |
| equivalent statements | statements with the same truth value |
| indirect reasoning | type of reasoning in which all possibilities are considered and then all but one are proved false. The remaining possibility must be true. |
| indirect proof | proof using indirect reasoning |
