Perimeter

Transcript

PerimeterSuppose we have a park like this And I run along the boundary from point A & back to point A This blue line is the perimeter of the figure Perimeter is distance along the boundary of a closed figure Let’s take some examples. Find Perimeter Perimeter = Sum of all sides = 40 + 10 + 40 + 10 = 100 cm Find Perimeter Perimeter = Sum of all sides = 5 + 5 + 5 + 5 = 20 cm Find Perimeter Perimeter = Sum of all sides = (3 + 1 + 3) + (3 + 1 + 3) + (3 + 1 + 3) + (3 + 1 + 3) = 7 + 7 + 7 + 7 = 28 cm Find Perimeter Perimeter = Sum of all sides = 100 + 120 + 90 + 45 + 60 + 80 = 220 + 135 + 140 = 355 + 140 = 495 m Perimeter of rectangle Let’s take a rectangle We know that In a rectangle, opposite sides are equal So, two sides have length l, and two sides have breadth b Now, Perimeter of rectangle = Sum of all sides = l + b + l + b = 2l + 2b = 2 (l + b) Thus, Perimeter of rectangle = 2 (l + b) Let’s do some examples Find perimeter of rectangle where length is 15cm & breadth is 9 cm Given, Length = l = 15 cm Breadth = b = 9 cm Perimeter of rectangle = 2 × (Length + Breadth) = 2 × (15 + 9) = 2 × 24 = 48 cm So, perimeter of rectangle is 48 cm Find perimeter of rectangle where length & breadth are 0.5 m & 0.2 m respectively. Given, Length = l = 0.5 cm Breadth = b = 0.2 cm Perimeter of rectangle = 2 × (Length + Breadth) = 2 × (0.5 + 0.2) = (2 × 0.7) = 1.4 m = 1.4 × 100 cm = 140 cm