Acute Angle
an angle with a measure between 0 and 90
Adjacent Angle
two angles that lie in the same plain, have a common vertex and side
Altitude
the height
Arc
Part of circle that is defined by 2 endpoints
Chord
a segment who endpoints on the circle
Circumference
the distance around the circle
Complementary Angle
two angles whose sum is 90
Congruent
same size and same shape
Decagon
a polygons with 10 sides
Diameter
chord that contains the center of the circle
Equiangular Triangle
a triangle with all angles congruent
Equilateral Triangle
a triangle with all sides congruent
Heptagon
a polygon with 7 sides
Hexagon
a polygon with 6 sides
Hypotenuse
side opposite the right angle in a triangle
Isosceles Triangle
a triangle with at least two sides congruent
Lateral Area
the sum of the areas of the sides
Leg
the side of a triangle
Line
made up of a point, has no thickness or width
Line Segment
a measurable part of a line
Midpoint
the point halfway between the endpoints of a segment
Nonoagon
a polygon with 9 sides
Obtuse Angle
an angle with a measure between 90 and 180
Octagon
a polygons with 8 sides
Parallel Lines
coplanar lines that do not intersect
Parallelogram
quadrilateral with 2 pair of parallel sides
Pentagon
a polygons with 5 sides
Perimeter
the sum of the lengths of the sides of a polygon
Perpendicular Lines
lines that form right angles
Plane
a flat surface made up of points
Point
a location
Quadrilateral
a polygon with 4 sides
Radius
segment that joins the center and any point on the circle
Ray
part of a line, has one endpoint and extend indefinitely in one direction
Rectangle
quadrilateral with 4 right angles
Regular Polygon
equiangular and equilateral
Rhombus
quadrilateral with 4 congruent sides
Right Angle
an angle with a measure of 90
Right Triangle
a triangle with a right angle
Scalene Triangle
a triangle with no sides congruent
Sector of a Circle
a region of a circle bounded by a central angle and its intercepted arcs
Skew Lines
noncoplanar lines that to not intersect
Square
quadrilateral with 4 right angles and 4 congruent sides
Supplementary Angles
two angles whose sum in 180
Theorem
a statement that can be proven
Total (Surface) Area
the sum of the areas of all sides and bases
Trapezoid
quadrilateral with exactly one pair of parallel sides
Triangle
a polygon with 3 sides
Vertical Angles
congruent, non-adjacent angles formed by 2 intersecting lines
Volume
a measure of the amount of space enclosed by a 3-D object