Page 282 - Start Up Mathematics_8 (Non CCE)

Some NCERT Textbook Questions

1. A flooring tile has the shape of a parallelogram whose base is 24 cm and the corresponding height is
2
10 cm. How many such tiles are required to cover a floor of area 1080 m ? (If required you can split the
tiles in whatever way you want to fill up the corners).
2. An ant is moving around a few food pieces of different shapes scattered on the floor. For which food-
piece would the ant have to take a longer round? Remember, circumference of a circle can be obtained
by using the expression c = 2pr, where r is the radius of the circle.
2.8 cm

(a) (b) 1.5 cm (c)

2.8 cm 2.8 cm 2 cm 2 cm

1 m
3. The shape of the top surface of a table is a trapezium. Find its area if its 0.8 m
parallel sides are 1 m and 1.2 m and perpendicular distance between them
is 0.8 m. 1.2 m

4. The floor of a building consists of 3000 tiles which are rhombus shaped and each of its diagonals are
2
45 cm and 30 cm in length. Find the total cost of polishing the floor, if the cost per m is ` 4.

Exemplar Problems

1. What is the area of the largest triangle that can be fitted into a rectangle of length l units and width w units?
lw lw lw lw
(a) (b) (c) (d)
2 3 6 4
2
2. Area of a quadrilateral ABCD is 20 cm and perpendiculars on BD from opposite vertices are 1 cm and
1.5 cm. The length of BD is:

(a) 4 cm (b) 15 cm (c) 16 cm (d) 18 cm

3. If the diagonals of a rhombus get doubled, then the area of the rhombus becomes ___________ its original
area.

4. The area of a trapezium becomes 4 times if its height gets doubled. (True/False)
2
5. The area of a rectangular field is 48 m and one of its sides is 6 m. How long will a lady take to cross the
field diagonally at the rate of 20 m/min?

6. Four horses are tethered with equal ropes at 4 corners of a square field of side 70 m so that they just can
reach one another. Find the area left ungrazed by the horses.

2
7. The area of a trapezium with equal non-parallel sides is 168 m . If the lengths of the parallel sides are
36 m and 20 m, find the length of the non-parallel sides.

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