
 Oblique:  Lines at an angle to the xaxis. 
 Oblique Prism:  A prisim with bases not aligned directly above one another. 
 Obtuse angle:  Any angle greater than 90 degrees and less than 180 degrees. 
 Obtuse Triangle:  A triangle with one obtuse angles. 
 Octa:  Prefix for 8 
 Octagon:  An eight sided polygon. 
 Octahedron:  A polyhedron with 8 faces. 
 Order of rotation:  How many times an outline matches its original during one full rotation. 
 Ordered Pair:  Where information is given through a pair of numbers and the order is critical. Ordered pairs are used in coordinate geometry to indicate a points position. (1,3) is not the same as (3,1) 
 Origin:  The point of intersection of the Xaxis and Yaxis on the cartesian plane. 
 Parallel lines:  Lines that will never intersect. 
 Parallelogram:  A quadrilateral with oposite sides equal in legth and parallel. 
 Pattern:  A repitition of objects. 
 Penta:  Prefix for 5 
 Pentagon:  A 5 sided polygon. 
 Pentahedron:  A Polyhedron with 5 faces. 
 Perimiter:  The outline of a two dimensional shape. 
 Perpendicular:  Two lines that meet at 90 degrees are said to be perpendicular. 
 Perpendicular Bisector:  A line that meets a line segment at 90 degrees AND bisects it. 
 Pi:  The ratio of a circles circumpherence to its diameter. 
 Plane Shape:  A flat shape with only two dimensions. 
 Platonic Solid:  Five Regular Polyhedra made only with either equilateral triangles, squares or pentagons. 
 Poly:  Prefix for MANY 
 Polygon:  A plane shape with three or more straight sides. 
 Polyhedron:  Three dimensional objects made with plane shapes. 
 Position:  Where something is when compared to an object or its surroundings. 
 Prism:  Right Prism: A three dimensional shape made of two identical plane shapes, and all other faces are rectangles; Oblique Prism: Made of two identical plane shapes, and all other faces are parallelograms. 
 Protractor:  An instrument used in geometric construction to measure degrees of angles. 
 Pyramid:  A three dimensional shape with a polygon as its base and all other faces congruent triangles that meet at the top (its vertex) 
 Pythagoras:  A Greek mathematician who lived circa 500BC. Famous for his theorem on Right Angled Triangles. 
 Pythagorean Theorem:  In a right angled triangle, the square of the hypotenuse is equal to the sum of the squares of the other two sides. 