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Arlene's Geometry
Arlene A's Class - Terms from Geometry in our Math block
| Term | Definition |
|---|---|
| point | has no length, width or thickness |
| line | has length but no width or thickness |
| plane | has length and width but no thickness |
| straight line segment | the part of a straight line between two of its points |
| midpoint | if a line is divided into two equal parts, this is the point of division |
| congruent segments | two segments having the same length are said to be this |
| circle | the set of all points in a plane that are the same distance from a point |
| circumference | distance around a circle |
| radius | a segment that joins the center of a circle to a point on the circle |
| central angle | an angle formed by two radii |
| chord | a segment joing any two points on a circle |
| diameter | a chord through the center of a circle |
| arc | a continuous part of the circle |
| semicircle | an arc measuring one half the circumference of a circle |
| congruent circles | circles having congruent radii are said to be this |
| angle | the figure formed by two rays with a common end point |
| acute angle | an angle whose measure is less than 90 degrees is said to be an |
| right angle | an angle that measures 90 degrees is said to be a |
| obtuse angle | an angle that measures more than 90 degrees and less than 180 degrees is said to be an |
| straight angle | an angle that measures 180 degrees is said to be a |
| reflex angle | an angle whos measure is more thatn 180 degrees and less than 360 degrees is said to be a |
| congruent angles | two angles that have the same number of degrees are said to be |
| angle bisector | a line that divides an angle into two equal parts |
| perpendicular | lines, rays or segments that meet at right angles are said to be |
| perpendicular bisector | a segment that is bisects and is perpendicular to another segment |
| polygon | a closed plane figure bounded by straight line segments at the sides |
| pentagon | a polygon with 5 sides |
| triangle | a polygon having three sides |
| vertex | the point at which two of sides of a polygon meet |
| scalene | a triangle that has no congruent sides |
| isosceles | a triangle that has at last two congruent sides |
| legs | the equal sides of an isosceles triangle |
| base angles | the angles on either side of the base of an isosceles triangle |
| base | the side of an isosceles triangle that are not the legs |
| equilateral | a triangle that has three congruent sides |
| right triangle | a triangle that has a right angle |
| obtuse triangle | a triangle that has an obtuse angle |
| acute triangle | a triangle that has three acute angles |
| angle bisector of a triangle's angle | a segment or ray that bisects the angle of triangle and extends to the opposite side |
| median of a triangle | a segment from a vertex to the midpoint of the opposite side |
| perpendicular bisector of a triangle's side | a line that bisects and is perpendicular to a side of a triangle |
| altitude of a triangle | a segment from the vertex of a triangle to the opposite side |
| outside the triangle | in an obtuse triangle, an altitude drawn on either side of an obtuse angle falls here |
| adjacent angles | two angles which have the same vertex and a common side |
| vertical angles | two nonadjacent angles formed by two intersecting lines |
| complementary angles | two angles whose measures add to 90 degrees |
| supplementary angles | two angles whose measures add to 180 degrees |
| transitive postulate | things equal to the same things are equal to each other |
| subtitution postulate | a quantity may be substituted for its equal in any expression or equation |
| partition postulate | the whole equals the sum of its parts |
| reflexive or identity postulate | any quantity equals itself |
| addition postulate | if equals are added to equals, the sums are equal |
| subtraction postulate | if equals are subtracted from equals, the differences are equal |
| multiplication postulate | if equals are multiplied by equals, the products are equal |
| division postulate | if equals are divided by equals, the quotients are equal |
| powers postulate | like powers of equals are equal |
| postulate 10 | like roots of equals are equal |
| one | the number of straight lines that can be drawn through any two points |
| theorem | a statement, which proved, can be used to prove other statements |
| CPCTC | congruent parts of congruent triangles are congruent |
| SAS | a way of proving two triangles are congruent when they have two sides and the included angle congruent to each other |
| orthocenter | the intersection point of a triangles altitudes |
| incenter | the angle bisectors of a triangle meet at this point |
| circumcenter | the perpendicular bisectors of the triangle meet at this point |
| centroid | the intersection point of the three medians in a triangle |
Created by:
cathyhk
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