The Facts On File Algebra Handbook

parallel planesTwo or more PLANEs that are exactly the same DISTANCE
apart. Parallel planes cannot intersect.

Pascal’s triangleOriginally used in India, and again in the mid-1500s,
this triangle was named after French mathematician BLAISE
PASCAL, who discovered new properties in the triangle he called
triangle arithmetique.This is a two-dimensional representation
of an ARITHMETIC SEQUENCE, beginning with 1 in the top row
(called Row 0), and 1 in the sides of the triangle, in which the
numbers next to each other in the triangle equal the number
below it.
See alsoSECTION IV CHARTS AND TABLES.

P.E.M.D.A.S.The ORDER OF OPERATIONSused to evaluate an EXPRESSION.
P.E.M.D.A.S. stands for Parentheses, Exponents, Multiplication,
Division, Addition, Subtraction.
See alsoSECTION IV CHARTS AND TABLES.

pentagonAPOLYGONwith five sides and five interior ANGLEs.

perfect numberAny NUMBERwhose FACTORs (excluding the number
itself), when added up, equal exactlythe number itself. For
example, the factors for the number 28 are 1, 2, 4, 7, and 14.
When these numbers are added, the SUMis 28, making this a
perfect number.

perfect squareAny WHOLE NUMBERthat is the exact SQUAREof another
whole number. For example, 2 is the exact square of 4, so 2 is a
perfect square. Other perfect squares include 1 (which is √
−
1 ), 3 (√
−
9 ),
4 (√
−
16), 5 (√
−
25), 6 (√
−
36), and so on.

perimeterThe DISTANCEaround a POLYGON. The length of the perimeter is
found by adding up the length of each of the sides.

perpendicularThe relationship of two lines that come together to form a
RIGHT ANGLE. The angle is a right angle, and the lines are
perpendicular.

pi (p) The RATIOof the CIRCUMFERENCEof a CIRCLEdivided by the
DIAMETER. The approximation of this IRRATIONAL NUMBERis usually
written as 3.1416.

plane A flat, straight, two-dimensional surface, which can be either real or
imaginary. An example of a plane with finite edges is a blackboard, a
tabletop, or a side of a CUBE. Some imaginary planes can be infinite

parallel planes – plane GLOSSARY

parallel planes – plane GLOSSARY

Pascal’s triangle

1 2 1

1 3 3 1

1 4 6 4 1

1 5 10 10 5 1

1 6 15 20 15 6 1

1 7 21 35 35 21 7 1

1 1

1

Pentagon

Perpendicular

Pi

π