P-II
57.
In trapezium PQRS, PQ || SR and the
ratio of PQ to SR is 3:2. If the area of
the trapezium is 480 cm? and the
distance between PQ and SR is 12 cm,
then the length of SR is
(1)
(2)
(3)
(4)
36 cm
48 cm
24 cm
32 cm
Answers
Answer:
seer the following:
11.5.2 Area of Circle
Amange the separate pieces as shown in Fig 11.36, which is roughly a parallelogram.
A farmer dug a flower bed of radius 7 m at the centre of a field. He needs to
dired
purchase fertiliser. If I kg of fertiliser is required for 1 square metre area.
how much fertiliser should he purchase?
. What will be the cost of polishing a circular table-top of radius 2 m at the rate
of 10 per square metre?
Can you tell what we need to find in such cases, Area or Perimeter? In such
makes we need to find the area of the circular region. Let us find the area of a circle, using
naphpaper.
Draw a circle of radius 4 cm on a graph paper (Fig 11.34). Find the area by counting
he number of squares enclosed.
As the edges are not straight, we get a rough estimate of the area of circle by this method,
71 side There is another way of finding the area of a circle.
Draw a circle and shade one half of the circle [Fig 11.350). Now fold the circle into
lero
sighths and cut along the folds (Fig 11.35(11)].
Fig 11.35
Fig 11.34
Fig 11.36