
Mathematical "O" Words oblique cone A cone whose axis is not perpendicular to its base. oblique
figure
A 3dimensional figure in which the plane of the base(s) is not perpendicular
to its axis or to the planes of its lateral surfaces. oblique line A line that is neither horizontal nor vertical. obtuse
angle
An angle whose measure is between 90° and 180°. Remember
a 90° angle is called a right angle not an obtuse angle, and a
180° angle is called a straight angle not an obtuse angle. obtuse triangle
A triangle with an obtuse angle. octagon An eightsided polygon. octahedron A polyhedron with eight faces. odd node
A node which is the endpoint of an odd number of arcs in a network. onedimensional A space in which all points are collinear. Basically a single line. onestep proof A justified conclusion of a conditional requiring a single definition, theorem, or postulate. open sentence A sentence with variables that can be true or false, depending on what is substituted for the variables.
Opop Property For all real numbers n: (n) = n. opposite When a given number is added to its opposite you always get ZERO. The opposite of a number n is denoted n. Also called additive inverse.
opposite faces A pair of faces of a polyhedron whose planes are parallel to each other. oppositely
congruent Figures
which are congruent and have opposite orientation. opposite
rays
Ray AB and Ray AC are opposite rays if and only if A is between B and
C. ordered
pair
A pair of numbers ( x, y ) in which x is the first coordinate and y is
the second coordinate. ordered
pair description of a vector
The description of a vector as the ordered pair
(a,b) where a is the horizontal component and b is the vertical component. order of operations Rules for evaluating an expression: work first within parentheses, then calculate all exponents, then do multiplication and division together as they appear in the problem from left to right; then do addition and subtraction as they appear from left to right.
orientation The order of the designation of the vertices of a polygon, either clockwise or counterclockwise.
origin The point where the x and y axes intersect denoted by ( 0, 0 ). ounce (oz) A unit of weight in the U.S. system of measurement equal to 1/16 of a pound. 1 ounce 29.574 milliliters. overlapping
figures
Figures which have some interior points in common. overlapping triangles Triangles that have interior points in common.
