# Find the perimeter of the lawn. Rani bought a new field that is next to one she already owns (Fig. 9.34). This field is in the shape of a square of 70 m. She makes a semi circular lawn of maximum area in this field.

**Solution:**

Given, Rani bought a new field that is next to one she already owns.

The new field is in the shape of a square of 70 m.

She makes a semicircular lawn of maximum area in this field.

We have to find the __perimeter__ of the lawn.

For maximum area, the side of the square will be the diameter of a semicircle.

Diameter = 70 m

Radius, r = 70/2 = 35 m

Perimeter of semicircular lawn = 2πr/2 + 2r

=πr + 2r

= r(π+2)

= 35 (22/7 + 2)

= 35 [(22+14)/7]

= 35 (36/7)

= 5(36)

= 180 m

Therefore, the perimeter of the lawn is 180 m.

**✦ Try This: **Pavi bought a new field that is next to one she already owns. This field is in the shape of a square of 100 m. She makes a semi circular lawn of maximum area in this field. Find the perimeter of the lawn.

**☛ Also Check: **NCERT Solutions for Class 7 Maths Chapter 11

**NCERT Exemplar Class 7 Maths Chapter 9 Problem 80(i)**

## Find the perimeter of the lawn. Rani bought a new field that is next to one she already owns (Fig. 9.34). This field is in the shape of a square of 70 m. She makes a semi circular lawn of maximum area in this field.

**Summary:**

Rani bought a new field that is next to one she already owns (Fig. 9.34). This field is in the shape of a square of 70 m. She makes a semi circular lawn of maximum area in this field. The perimeter of the lawn is 180 m

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