CHAPTER 3: MENSURATION

Question 1

What is the area of a rectangle?

Answer 1

Area= Length x Width

Question 2

What is the area of a trapezium?

Answer 2

area= 1/2( a+b)h

Question 3

What is the area of a kite?

Answer 3

1/2(a x b)
or 1/2 x (product of diagonals)

or

  1
 --- d1 x d2
  2

Question 4

What is the area of a triangle?

Answer 4

1/2 base x height

Question 5

What is the formula used to find the height of a triangle when two sides and an included angle are known?

Answer 5

1/2 x b x a Sin C

b= base of entire triangle(length).
a= length of the side of a triangle. When you split the triangle into two to find the height, 'a' is usually the hypotenuse.
c= the included angle.

Question 6

What is the area of a parallelogram?

Answer 6

Area= base x height

Question 7

What if the height of the paralleogram not given?

Answer 7

area= ba sin 0
a= length of the side of a triangle. When you split the triangle into two to find the height, 'a' is usually the hypotenuse.

Question 8

What is the circumference (perimeter) of a circle?

Answer 8

2πr

or πd

Question 9

What is the ratio of a circle?

Answer 9

circumference ÷ diameter

Question 10

What is the area of a circle?

Answer 10

A=πr2

Question 11

What is the formula of the arc length of a circle?

Answer 11

Arc length= 0
——- x 2πr
360

Question 12

What is the formula of sector area?

Answer 12

Sector area= 0
—— x πr2
360

Question 13

CHORD:

Answer 13

1. The area of a circle cut off by a chord is called a segment.
2. The line from the centre of a circle to the midpoint of a chord bisects the chord at right angles.
3. The line from the centre of a circle to the midpoint of a chord bisects the angle subtended by the chord at the centre of the circle.

Question 14

How to find the area of a segment(minor arc)?

Answer 14

Area of segment= Area of sector - Area of triangle( at the centre of the circle)

Question 15

What is the volume of a prism?

Answer 15

Volume= area of cross sectional area x length

Question 16

Cuboid:

Answer 16

A cuboid is a prism whose six faces are all rectangles.

Question 17

Cube:

Answer 17

A cube is a special case of a cuboid in which all six faces are squares.

Question 18

What is the volume of a cone?

Answer 18

l
—- x πr2h
3

Question 19

What is the volume of a sphere?

Answer 19

4
—- x πr3
3

Question 20

What is the volume of a pyramid?

Answer 20

1
—- x bh
3

Question 21

What is the volume of a cylinder

Answer 21

πr2h

Question 22

What is the surface area of a cylinder?

Answer 22

Total surface area

2πrh + 2πr2

Lateral surface area (curved surface area)

2πrh

Question 23

What is the surface area of a cone?

Answer 23

Total surface area

πr2 + πrl

Lateral surface area (curved surface area)

πrl

Question 24

what is “ l “?

Answer 24

Slant Height.

Question 25

What is the surface area of a sphere?

Answer 25

Total surface area

4πr2

Lateral surface area (curved surface area)

4πr2