Basics
A straight path with two end points.
Line Segment.
An angle measuring less than 90 degrees.
Acute.
A triangle with a 90 degree angle in it.
Right triangle.
A quadrilateral with 2 pairs of parallel lines, doesn't have 4 equal sides and no right angles.
Parallelogram.
A fully enclosed shape with all straight sides.
Polygon.
A straight path that goes forever in both directions.
Line.
An angle measuring exactly 90 degrees.
Right.
A triangle with 1 angle that measures greater than 90 degrees.
Obtuse triangle.
A quadrilateral with 2 pairs of parallel lines, 4 equal sides and no right angles.
Rhombus.
A polygon with 5 sides.
Pentagon.
A straight path with 1 end point and goes forever in one direction.
Ray.
An angle measuring more than 90 degrees but less than 180 degrees.
Obtuse.
A triangle with all equal sides.
Equilateral triangle.
A quadrilateral with 2 pairs of parallel lines, 4 equal sides and 4 right angles.
Square.
A polygon with 6 sides.
Hexagon.
When 2 lines, segments or rays would never intersect if continued forever.
Parallel.
An angle measuring exactly 180 degrees.
Straight.
A triangle with 2 equal sides.
Isosceles triangle.
A quadrilateral with 2 pairs of parallel sides, 4 right angles but doesn't have 4 equal sides.
Rectangle.
A polygon with 8 sides.
Octagon.
When 2 lines, segments or rays intersect and form a right angle.
Perpendicular.
An angle measuring greater than 180 degrees.
Reflex.
A triangle with no equal sides.
Scalene triangle.
A quadrilateral with only 1 pair of parallel sides.
Trapezoid.
A polygon with 10 sides.
Decagon.