Quadrilateral
Polygon with four sides
Pentagon
Polygon with five sides
Hexagon
Polygon with six sides
Heptagon
Polygon with seven sides
Octagon
Polygon with eight sides
Nonagon
Polygon with nine sides
Decagon
Polygon with ten sides
Parallelogram
A quadrilateral with two pairs of parallel sides.
Rectangle
A quadrilateral with four 90 degrees angles.
Square
A quadrilateral with four 90 degrees angles and four equal sides.
Rhombus
A quadrilateral with four equal sides.
Trapezoid
A quadrilateral with only one pair of parallel sides
Kite
A quadrilateral with two pairs of equal sides
the pairs have different lengths the sides with equal lengths are next to each other.
Concave Polygons
Polygons have at least one point going in.
Convex Polygons
Polygons have all points going out
Lines
have no end points - they extend forever in two directions.
Rays
have one end point - they extend forever in one direction.
Segments
have two end points - they have ends in two directions.
Angle Bisector
divides an angle equally in half
Perpendicular Bisector
divides a straight angle equally in half to make two right angles
Planes
have no edges - they extend forever in two directions.
Scalene triangle
No equal sides
Isosceles triangle
Two equal sides
Equilateral triangle
Three equal sides
Acute triangle
All angles less than 90
Right triangle
One angle equals 90
Obtuse triangle
One angle more than 90
Transversal
a line that cuts two or more parallel lines
Corresponding Angles
Are in matching positions compared to the parallel lines and the transversal.
Alternate Interior Angles
Are between the parallel lines and diagonally opposite.
Alternate Exterior Angles
Are outside the parallel lines and diagonally opposite.
Vertical Angles
Are opposite each other on a pair of crossed lines
Same side interior angles
Are between the parallel lines and on the same side of the transversal.
Same side exterior Angles
Are outside the parallel lines and on the same side of the transversal.
Supplementary Angles
Have a sum of 180
Complementary Angles
Have a sum of 90.
The sum of angles in a polygon
(number of sides - 2) x 180
interior angle
((number of sides - 2) x180) / number of sides