| A | B |
|---|
| acute triangle | all angles less than 90 degrees |
| adjacent interior angles | angle within a triangle that's next to the exterior angle |
| base of a triangle | the bottom side |
| collinear points | three in a row form a line |
| conclusion | the ending statement in a proof |
| coordinate plane | x-y axis and all points on them |
| equiangular triangle | all three angles are equal |
| equilateral triangle | all three sides are equal |
| exterior angle | formed by extending one side of the triangle |
| given | facts in a proof that you begin with |
| indirect reasoning | list all the possible solutions, then show that all but one are impossible |
| isosceles triangle | two sides are equal |
| noncollinear points | points not on the same line |
| obtuse triangle | one angle is greater than 90 degrees |
| ordered pair | point on the (x,y) plane |
| origin | point of interesection on a plane (0,0) |
| parallel lines | two lines that run next to each other and never cross |
| postulate | statement assumed to be true in all cases |
| remote interior angles | the sum of two remote interior angles equals the exterior angle |
| right triangle | one angle equals 90 degrees |
| scalene triangle | none of the sides are equal |
| slash mark (tick mark) | shows equal angles or sides |
| theorem | statement found true in all cases due to deductive reasoning |
| triangle | figure consisting of 3 noncollinear points and their connecting line segments |
| triangle inequality | the difference of the sides < x < the sum of the sides |
| two-column proof | statements in one column and the reasons in another |
| x-coordinate | the first number in an ordered pair; runs horizontal |
| y-coordinate | the second number in an ordered pair; runs vertical |
