Parallel Lines        Congruent Tri.        Congruent R. Tri.        Isosc. and Equil.        Quadrilaterals        Parallelograms        Ratios        Similar Polygons        Special Triangles       Circles    Area        Coordinate Geo.        Triangle Ineq.        Solids        Computer Fun

On this page, we hope to clear up problems that you might have with area of polygons.  The way it is laid out is as follows:  Throughout our math experience, we have found it would be nice to have a comprehensive listing of all the different formulas you need to know to find the area of polygons.  We have done that with one significant addition - figures that help make the formula actually make sense!  Scroll down or click one of the links below to start understanding how to find the area of polygons! Rectangles Squares Triangles Parallelograms Rhombuses Trapezoids Circles and sectors Other polygons Quiz on Area Rectangle Area Postulate The area A of any rectangle is equal to the product of the length l and the width w. Formula: A = lw Back to Top  Square Area Theorem The area A of any square is equal to the square of the length s of a side. Formula: A = s2 Back to Top  Triangle Area Theorem The area A of any triangle is equal to one-half the product of any base b and corresponding height h. Formula: A = .5bh Back to Top  Parallelogram Area Theorem The area A of any parallelogram is equal to the product of any base b and the corresponding height h. Formula: A = bh Back to Top  Rhombus Area Theorem The area A of any rhombus is equal to one-half the product of the lengths d1 and d2 of its diagonals. Formula: A = .5d1d2 Back to Top  Trapezoid Area Theorem The area A of any trapezoid is equal to one-half the product of the height h and the sum of the bases, b1 and b2. Formula: A = .5h(b1 + b2) Back to Top  Circle Area Postulate The area A of any circle is equal to the product of PI and the square of the radius r. Formula: A = (PI)r2 Sector Area Theorem The area A of any sector with an arc that has degree measure n and with radius r is equal to the product of the arc's measure divided by 360 multiplied by PI times the square of the radius. Formula: A = (n/360)((PI)r2) Back to Top  Regular polygons are any polygons that are equilateral and equiangular. Regular Polygon Area Theorem The area A of any regular polygon with perimeter P and apothem of measure a is equal to one-half the product of the perimeter and the apothem. Formula: A = .5aP Back to Top  Take the Quiz on area.  (Very useful to review or to see if you've really got this topic down.)  Do it!