MENSURATION AND SURVEYING 



1!) 



MENSURATION AND SURVEYING. 



Area of rectangle — length X breadth. 



Area of square = any side X itself. 



Area of parallelogram = base X perpendicular height. 



Area of trapezoid = half the sum of the parallel sides X 

 perpendicular height. » 



Area of trapezium or any quadrilateral = sum of the two 

 triangles of which it is composed. 



Area of triangle = half the product of the base into the 

 __. , . , . ABXC5 

 perpendicular height or k~ * 



ADBADB AB D 



or if s = half th e sum of the three sides o, h. e, the area = 

 -/ s (s --a) (» — b) (s -- c) 

 (a) Area of a circle = diameter 2 x '7854. 



To multiply by '7854, multiply by 7 and then by 2 

 moving the rows one place to the right, as shown below : — 



865 



7 



6055 

 6055 

 12110 

 12110 



7 



14 

 14 



079-3710 



7854 



22 



7 



or the dia- 



The circumference = twice the radius X 

 22 



7 

 (6) Area = circumference X half the radius or if r 



meter X 



the radius.^area 



, 22 



29 



r* 



7 ^ 2 "~ 7 

 (c) Area = (the circumference) 2 x "08 



Area of a sector of la circle = length of the arc X half th<* 

 radius. 



