a In the figure i given below the boundary of the shaded region in the given diagram consists of fou...

Question

a In the figure i given below the boundary of the shaded region in the given diagram consists of four semicircular arcs the smallest two being equal If the diameter of the largest is 14 cm and of the smallest is 35 cm calculate i the length of the boundary ii the area of the shaded region b In the figure ii given below a piece of cardboard in the shape of a trapezium ABCD AB CD and BOD quarter circle BFEC is removed Given AB BC 35 cm and DE 2 cm Calculate the area of the remaining piece of the cardboard

Accepted Answer

Perimeter for irregular shape is equal to the length of the boundary.

The area of irregular shapes refers to the area that the shape covers. Irregular forms are those that don't have the same number of sides or angles on all sides. To calculate the area of an irregular form, it must first be decomposed or divided into several common shapes, and then the areas of those shapes must be summed to obtain the total area.

(a) (i) We know that

Length of boundary = Circumference of bigger semi-circle + Circumference of small semi-circle + 2 ×

circumference of the smaller semi-circles

M L Aggarwal - Understanding ICSE Mathematics - Class 9 chapter Mensuration Question 21 Solution image

(b) Here

M L Aggarwal - Understanding ICSE Mathematics - Class 9 chapter Mensuration Question 21 Solution image

ML Aggarwal Solutions Class 9 Mathematics Solutions for Mensuration Exercise 16.3 in Chapter 16 - Mensuration