# Polygon - Mount Saint Mary College Geometry 2 Dimensional Shapes Polygon Simple, closed figure made up of line segments which intersect in exactly two places Regular polygon: all sides are equal all interior angles are equal Quadrilateral: polygon with 4 sides

Parallelogram 2 pair of parallel sides Height Base Area = base x height A = bh

Trapezoid One pair of parallel sides a Height b Area = height x (base 1 + base 2)

2 A = h(a+b) 2 Rectangle Interior angles are all 90 length width Area

= length x width A = lw Square Rectangle Area with 4 equal sides = side x side A = s2

Rhombus 4 equal sides Area: The area of a rhombus is A= (1/2) d1 * d2 , where d1 is the length of the first diagonal and d2 is the length of the second diagonal.

Triangles: 3 sided polygon Right: angle has a 90 Equilateral: sides equal

Isosceles sides Scalene: sides : 2 equal no equal All

triangles Area = base x height A = bh height height base Right triangles: a2 + b2 = c2 base

Summary of Polygons polygons and characteristics Circle Set of all points in a plane that are a fixed distance from a given point (the center) Radius Perimeter = circumference

P = 2 r Area = pi x radius squared Area= r2