Perimeters And Areas Of Plane Figures — Chapter Summary

Perimeter is the total length

Perimeter is the total length of the boundary of a figure. For a rectangle with length l and breadth b, the perimeter is 2(l+b). For a square of side

Area is the amount of surface

Area is the amount of surface enclosed by the boundary. Common formulas include rectangle: lb, square: a^2, parallelogram: b × h, triangle: 1/2 × b ×

For a triangle with sides

For a triangle with sides a, b, c, the semi-perimeter is s = (a+b+c)/2 and the area is √(s(s-a)(s-b)(s-c)). This formula is useful when the height is

A path around a rectangle

A path around a rectangle of length l and breadth b with width w has area (l+2w)(b+2w) - lb. For two cross paths through the middle of a rectangle, th

For a circle of radius r

For a circle of radius r, circumference = 2πr and area = πr^2. The chapter uses π ≈ 22/7 and also notes Aryabhata’s value π ≈ 3.1416.