1. The radius of sphere is r cm. It is divided into . two equal parts. The whole surface area of two parts will be

2. If the diameter of a semicircular protractor is 14 cm, then its perimeter is .

3. A race track is in the form of a circular ring whose outer and inner circumferences are 396 m and 352 m respectively. The width of the track is

4. The area of the largest square that can be inscribed in a circle of radius 12 cm is

5. The area of the largest triangle that can be inscribed in a semicircle of radius r is

6. The area (in cm²) of the circle that can be inscribed in a square of side 8 cm is

7. If the perimeter of a circle is equal to that of a square, then the ratio of their areas is

8. The circumference of two concentric circles forming a ring are 88 cm and 66 cm. Taking π =\(\frac{22}{7}\), the width of the ring is

9. A steel wire when bent in the form of a square encloses an area of 121 cm². If the same wire is bent in the form of a circle, then the circumference of the circle is

10. The diameter of a circle whose area is equal to sum of the areas of the two circles of radii 40 cm and 9 cm is