Polygon/Circle |P = Perimeter C = Circumference distance around the polygon/circle | A = Area the surface inside the boundary( perimeter) | | |triangle | [pic] |[pic] | |a = altitude |P = b + c + d |A = 1/2ab | |b = base |or |Note: The area of the triangle is half the area | | |P = s1 + s2 + s3 |of the corresponding parallelogram/rectangle. | |quadrilateral |[pic] |don't need to memorize the formula in junior | | |P = b + c + d + e |high | | |or |enrichment | | |P = s1 + s2 + s3 + s4 | | |trapezoid | [pic] |[pic] | |a = altitude |P = b1 + b2 + c + d |A = 1/2ab1 + 1/2ab2) | |b = base |or |simplifies to | | |P = s1 + s2 + s3 + s4 |A = 1/2a(b1 + b2) | |parallelogram |[pic] |[pic] | |a = altitude |P = 2b + 2c |A = bh | |b = base | | | | | | | |rhombus |[pic] |[pic] | |a = altitude |P = 4s |A = as | |s = side length | | | | | | | |rectangle |P = 2l + 2w |A = lw | |l = length |[pic] |[pic] | |w = width | | | | | | | |square |[pic] |[pic] | |s = side length |

P = 4s |A = s2 | | | | | |chevron |[pic] |don't need to memorize the area formulae in | | |P = 2c + 2d |junior high | | | | | |kite |[pic] |don't need to memorize the area formulae in | | |P = 2c + 2d |junior high | | | |enrichment | |regular polygon |P = ns |A = 0.5ans = 0.5aP | |a = apothem length |[pic] |[pic] | |s = side length | | | |n = #sides | | | | || | |pentagon = "five sides" | | | |hexatagon = "six sides" | | | |heptaagon = "seven sides" | | | |octaagon = "eight sides" | | | |nonagon = "nine sides" | | | |decagon = "ten sides" | | | | | | |

circle |C = Circumference |A = Area | |[pic] |C = pd |A = p r2 | |Circumference is the distance | | | |around the circle. | | | |r = radius of circle | | | |d = diameter of circle | | | | | | | | |[pic] | | | | |Relationships: |1. For a square, non-square rectangle and circle |1. For a square, non-square rectangle and circle| | |with equal perimeter/circumference the relative |with equal areas the relative perimeter from | | |area from largest to smallest is: |largest to smallest is: | | |circle, square, rectangle |rectangle, square, circle | | |

2. Increasing dimensions by a factor increases the|2. Increasing the dimensions by a factor | | |perimeter by the same factor. |increases the area by the square of the factor. | | |tripling the dimensions triples the perimeter |tripling the dimensions increases the area by a | | | |factor of 9 (32). | | Polygon/Circle |Perimeter/Circumference |Area |