# CBSE Class 10-Mathematics: Chapter –12 Areas Related to Circles Part 13

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Question 38:

The cost of fencing a circular field at the rate of per metre is . The field is to be ploughed at the rate of . Find the cost of ploughing the field.

Since for , the length of fencing metre

for , the length fencing

Perimeter i.e., circumference of the field

Let r be the radius of the field

Area of the field

Total cost of ploughing the field = Rs.

Question 39:

Find the difference between the area of regular hexagonal plot each of whose side 72m and the area of the circular swimming take in scribed in it. (Take

Side of hexagonal plot Area of equilateral triangle

Area of hexagonal plot Area of triangle OAB

Area of circular region

Difference

Question 40:

In the given figure areas have been drawn of radius each with vertices A, B, C and D of quadrilateral ABCD as centers. Find the area of the shaded region.