51.

A circle and a rectangle have the same perimeter. The sides of the rectangle are 18 cm and 26 cm. The area of the circle is 

• 125 cm²

• 230 cm²

• 550 cm²

• 550 cm²

The area of a circle is increased by 22 cm² when its radius is increased by 1 cm. The original radius of the circle is

• 3 cm

• 5 cm

• 7 cm

• 7 cm

• 256 sq. cm.

• 250 sq. cm.

• 128 sq. cm.

• 128 sq. cm.

The lengths of three medians of a triangle are 9cm, 12cm and 15 cm. The area (in sq. cm) of the triangle is

• 24

• 72

• 48

• 48

If the diagonals of a rhombus are 8 and 6, then the square of its side is

• 25

• 55

• 64

• 64

A playground is in the shape of a rectangle. A sum of ₹ 1,000 was spent to make the ground usable at the rate of 25 paise per sq. m. The breadth of the ground is 50 m. If the length of the ground is increased by 20 m, what will be the expenditure in rupees at the same rate per sq. m.?

• 1,250

• 1,000

• 1,500

• 1,500

In a triangle ABC, AB + BC = 12 Cm,   BC + CA = 14 cm and CA + AB = 18 cm. Find the radius of the circle (in cm) which has the same perimeter as the triangle.

If the length of a rectangle is increased by 10% and its breadth is decreased by 10%, then its area

• decrease by 1%

• increases by 1%

• decreases by 2%

• decreases by 2%

A wire, when bent in the form of a square, encloses a region of area 121 cm². If the same wire is bent into the form of a circle, then the area of the circle is  

• 150 cm²

• 152 cm²

• 154 cm²

• 154 cm²

The ratio of the area of a sector of a circle to the area of the circle is 1 : 4. If the area of the circle is 154 cm², the perimeter of the sector is

• 20 cm

• 25 cm

• 36 cm

• 36 cm