Classifying 2-D Figures
5.5A
Vocabulary Focus
Acute Angle
an angle measuring less than 90 degrees
Acute Triangle
a triangle with three acute angles
Adjacent Angles
side-by-side;adjoining
Congruent
having the same size and shape
Degree
a unit of measure for angles and temperature
Equilateral Triangle
a triangle with three congruent sides and three congruent angles
isosceles triangle
a triangle with two congruent sides and two congruent angles (?)
kite
a quadrilateral with two pairs of congruent, adjacent sides
obtuse angle
an angle that measures more than 90 degrees but less than 180 degrees
Obtuse Triangle
a triangle that has one angle greater than 90 degrees
Parallel Lines
Two lines that are in the same plane that never intersect.
Perpendicular lines
intersecting at right angles.
Polygons
A closed figure made out of segments
Quadrilateral
a polygon with four sides and four angles
Rectangle
a parallelogram with four right angles
Rhombus
a parallelogram in which all four sides are congruent and opposite angles are congruent
Right Angle
an angle with a measure of 90 degrees
Right Triangle
a triangle with one right angle
Scalene Triangle
a triangle with no congruent sides
Sides
one of the lines that make a shape
Square
a special rectangle with 4 sides of equal measure
Trapezoid
a quadrilateral with one pair of parallel sides
Triangle
a three sided figure
2-Dimensional Figures
a plane figure that has length and width: area and perimeter
Regular Polygon
a polygon in which all sides and all angles are congruent
Irregular Polygon
a polygon with sides and angles that are not congruent or equal
Pentagon
A 5 sided polygon
Hexagon
a six sided polgon
Heptagon
a 7 sided polygon
Octagon
an 8 sided polygon
Parallelogram
a quadrilateral with opposite sides that are parallel and congruent
Nonagon
a 9 sided polygon
Decagon
a 10 sided polygon