MAT091 Basic Math Skills Module G Supplement – Sec. 6.2 Polygon Names Name of Polygon Number of Sides Example Other Special Characteristics Triangle 3 The sum of the measures of the three angles is 180° in every triangle Quadrilateral 4 [ See examples of special kinds of quadrilaterals on the back → ] Pentagon 5 Hexagon 6 Heptagon 7 Octagon 8 Nonagon 9 Decagon 10 Dodecagon 12 Name of Polygon Trapezoid Number of Sides 4 Example Other Special Characteristics One pair of parallel sides [A trapezoid is also a special kind of quadrilateral] Parallelogram 4 Two pairs of parallel sides [A parallelogram is a special kind of quadrilateral] Rhombus 4 Two pairs of parallel sides; all 4 sides equal [A rhombus is also a special kind of parallelogram] Rectangle 4 Four right angles (90°); (opposite sides parallel) [A rectangle is also a special kind of quadrilateral and parallelogram] Square 4 Four right angles (90°); all 4 sides equal in length [A square is also a special kind of quadrilateral, parallelogram, rhombus, and rectangle] Lessons 6.2-6.5 – Perimeter, Circumference, Area, and Volume Formulas to Memorize: Perimeter of any Polygon: (Just add the lengths of all the sides) Circumference of a Circle: C = 2πr or C = πd [ where r = radius, d = diameter ] Area of a Circle: A = πr2 Area of a Rectangle: [ where L = length, W = width ] A = LW [ Also remember that a square is just a rectangle with equal sides, so L = W. ] Area of a Parallelogram: A = bh [ where b = base, h = height ] Area of a Triangle: A = ½bh or A = (bh)/2 Area of a Trapezoid: A = ½h(b+c) [since a triangle is half of a parallelogram] [ where b and c are lengths of two parallel sides ] Volume of a Rectangular Solid* (box with rectangular sides): V = LWH Volume of a Cylinder*: V = πr2h [*Notice that to find the volume of a solid figure with straight sides where the parallel base and top surfaces are exactly the same, we just multiply the area of the base by the height of the figure.]