INDIAN SCHOOL - AL GHUBRA
Department of mathematics -- class – 9
Assignment - Mensuration of plane figures
1.
Find the area of an equilateral triangle whose perimeter is 12 cm.
2.
Using Hero’s formula , find the area of a triangle whose sides measure 30 cm,
24cm , and 18cm.
3.
The sides of a triangle are 14cm , 24cm and 26cm.Find the altitude corresponding
to the side of length 24cm.
4.
The perimeter of a right triangle is 40cm. Its hypotenuse is 17cm. Find the sides
containing the right triangle. Also find the area of the triangle.
5.
A parallelogram has sides 30cm and 14cm. One of its diagonal is 40cm. Find its area.
6.
A parallelogram has its adjacent sides 10m and 8m.If the distance between the longer
sides is 4m find the distance between the shorter sides.
7.
A wire is in the form of a circle of radius 35cm.It is bent in the form of a square. Find
the area of the square.
8.
The minute hand of a clock is 10cm long. Find the area swept by the minute hand
between 8:00a.m and 8:25 a.m.
9.
A chord of a circle of radius 14cm makes an angle of 60 at the center of a circle.
Find the area of the minor segment of the circle.
10.
The area of an equilateral triangle is 1963 cm2. With each vertex as center a circle is
described with radius equal to half the length of the side of the triangle. Find the area
of the triangle not included in the circles. (  = 22/ 7 )
11.
A square lawn is surrounded by a path 3m wide around it. If the area of the path is
180 sq m , find the area of the lawn.
12.
Four equal circles are described about the four corners of a square so that each
touches two of the others. Find the area of the space enclosed between the
circumferences of the circles , each side of the square measuring 14cm .
13.
The perimeter of a certain sector of a circle of radius 5.7 m is 27.2m. Find the area of
the sector.
14.
A horse is tethered in a corner of a rectangular field 40m x 25m with a rope 14m
long. How much area of the field it can graze.
15.
OABC is a rhombus whose three vertices A , B , and C lie on a circle with center O.
If the radius of the circle is 10cm, find the area of the rhombus.
16.
The cross – section of a canal is a trapezium in shape. If the canal is 10m wide at the
top , 6m wide at the bottom and the area of the cross- section is 72 sq m , find its
depth.
17.
Find the area of the trapezium in the figure. ( 15 = 3.873 )
A
26m
B
16m
18.
16m
C
34m
D
Find the area enclosed by the shaded region in the figure. Also find the perimeter of
the shaded region.
19.
In the figure AOB is a quadrant of a circle and a semicircle with AB as a diameter is
drawn. Find the area of the shaded region.
20.
In the given figure , ABCD is a trapezium. AE is 2cm. Find the area of the shaded
region.
ANSWERS :
1.
43 sq cm
2.
216 sq cm
3.
83 cm
4.
15 cm , 8cm , 60 sq cm
5.
336 sq cm
6.
5m
7.
3025 sq cm
8.
130.95 sq cm
9.
18.8 sq cm
10.
31.472 sq cm
11.
144 sq m
12.
42 sq cm
14.
154 sq m
15.
503 sq cm
17.
464.76 sq cm
18.
19.
98 sq cm
20. 6.125 sq cm
13.
16.
45.04 sq m
9m
cm , 22cm
19.25 sq