Areassquare = a2 rectangle = ab parallelogram = bh trapezoid = h/2 (b1 + b2) circle = pi r 2 ellipse = pi r1 r2 triangle = (1/2) b h equilateral triangle = (1/4) (3) a2 triangle given SAS = (1/2) a b sin C triangle given a,b,c = s(s-a)(s-b)(s-c) when s = (a+b+c)/2 (Heron’s formula) regular polygon = (1/2) n sin(360°/n) S2when n = # of sides and S = length from center to a corner ________________________________________Volumescube = a3 rectangular prism = a b c irregular prism = b h cylinder = b h = r2 h pyramid = (1/3) b h cone = (1/3) b h = 1/3 r2 h sphere = (4/3) r3 ellipsoid = (4/3) pi r1 r2 r3 ________________________________________Surface Areascube = 6 a2 prism: (lateral area) = perimeter(b) L (total area) = perimeter(b) L + 2b sphere = 4 r2