# Mensuration

Formula list of figures

 Name Figure Perimeter Area in square Rectangle a = length b = breadth 2(a + b) ab Square a = side 4a a^2 1/2 (diagonal)^2 Parallelogram a = side b = side adjacent to a h = distance between the opp. parallel sides 2(a + b) ah Rhombus a = side of rhombus; d1,d2 are the two diagonals 4a 1/2*d1*d2 Quadrilateral AC is one of its diagonalsand h1, h2 are the altitudes on AC from D, B respectively. Sum of its four Sides 1/2 (AC) (h1 + h2) Trapezium a, b, are parallel sides and h is the distance between parallel sides Sum of its four sides 1/2 h(a + b) Triangle b is the base and h is the altitude.a, b, c are three sides a + b + c = 2s 1/2 b × h or s(s - a)(s -b)(s - c) Right triangle d^2(hypotenuse)= b^2 + h^2 b + h + d 1/2 bh Equilateral triangle a = side h = altitude =root(3)/2 a 3a (i)1/2 ah (ii)root(3)/4 a^2 Isosceles Triangle c = unequal side a = equal side 2a + c C* root(4a^2 - c^2)/ 4 Isosceles Right Triangle d(hypotenuse)= a Root(2) a = Each of equal sides. The angles are 90,45, 45. 2a + d 1/2 a2 Circle r = radius of the circle p- =22/7 or 3.1416 2pi r pi* ^2 Semicircle r = radius of the circle pr + 2r 1/2*pi*r^2