Term | Definition |
Point | an exact location on a line, in a plane or in space |
Line | A straight path of points that goes on forever in opposite directions |
line segment | part of a line with two end points and all the points between them |
ray | a part of a line that begins at one end point and goes on forever in one direction |
plane | a flat surface of points that continues without end in all directions named by at least three points |
intersecting lines | lines that cross each other at one point |
parallel lines | lines in the same plane that never intersect and are always the same distance apart |
perpendicular lines | lines that intersect to form four right angles (90 degrees) |
angle | two rays with the same end point |
vertex | end point at which two rays meet in an angle |
protractor | tool used to measure the degree of an angle |
right angle | an angle that measures exactly 90 degrees and forms a square corner |
acute angle | angle that measures greater than 0 degrees and less than 90 degrees |
obtuse angle | angle that measures greater than 90 degrees and less than 10 degrees |
straight angle | angle that measures exactly 180 degrees and forms a line. |
equilateral triangle | a triangle with 3 equal sides |
isosceles triangle | a triangle with 2 equal sides |
scalene triangle | a triangle with no equal sides |
right triangle | a triangle that has a right angle (measures 90 degrees) |
acute triangle | a triangle that has three acute angles that measure less than 90 degrees |
obtuse triangle | a triangle that has one obtuse angle that measures more than 90 degrees |
parallelogram | a quadrilateral with all sides parallel and opposite sides equal |
rhombus | a parallelogram with four equal sides |
trapezoid | a quadrilateral with only one pair of parallel sides |
square | a plane figure with four equal sides and four right angles |
rectangle | a plane figure with two pairs of equal sides and four right angles |
polygon | a closed plane figure with sides formed by 3 or more line segments |
triangle | a polygon with 3 sides and 3 angles |
quadrilateral | a polygon with 4 sides and 4 angles |
pentagon | a polygon with 5 sides and 5 angles |
hexagon | a polygon with 6 sides and 6 angles |
octagon | a polygon with 8 sides and 8 angles |
regular polygon | a polygon in which all sides have equal length and all angles have equal measure |
irregular polygon | a polygon in which all the sides are not equal length and the angles do not have equal measure |
circle | a closed plane figure made up of many points that are the same distance from the center |
center | the point from which every point in a circle is exactly the same distance |
chord | a line segment that has its endpoints on the circle |
diameter | a chord that passes through the center of a circle |
radius | a line segment with one end point at the center of a circle and the other end point on the circle |
compas | a tool used to construct circles |