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

The sum of all interior angles of a regular polygon is twice the sum of all its exterior angles. The number of sides of the polygon is

• 10

• 8

• 12

• 12

The height of a right prism with a square base is 15 cm. If the area of the total surfaces of the prism is 608 sq. cm. its volume is

• 910 cm³

• 920 cm³

• 960 cm³

• 960 cm³

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

• 25

• 55

• 64

• 64

The volume of a solid hemisphere is 19404 cm³. Its total surface area is

• 4158 cm²

• 2858 cm²

• 1738 cm²

• 1738 cm²

If m and n are positive integers and (m - n) is an even number, then (m² - n²) will be always divisible by

• 4

• 6

• 8

• 8

If , then the value of (x⁷² + x⁶⁶ + x⁵⁴ + x³⁶ + x²⁴ + x⁶ +1) is

• 1

• 2

• 3

• 3

If a + b + c = 0, then the value of  is

• 0

• 1

• 2

• 2

69.

If  then the value of  is

• 

• 4

• -4

• -4

If a + b + c = 6,  a² + b² + c² = 14  and a³ + b³ + c³ = 36, then the value of abc is

• 3

• 6

• 9

• 9