Worked out Examples
the area of the triangle with sides 12 cm, 13 cm and 15 cm?
three sides a, b and c of a triangle are given,
then its area =
Where s = = 20 cm
The area of the base of a right circular cone
is 154 cm2 and its vertical height is 24 cm. What is its curved
surface area? .
the base = pr2 = 154 ⇒ r = 7 cm.
Slant height = = = 25 cm
\ Curved surface area = prl = x 7 x 25
= 550 cm2.
What is the area of a regular hexagon whose
side measures 4 cm?
The hexagon can be divided into six
equilateral triangles of equal areas. Area of the hexagon = 6 x x 4 x 4 =
The radius of the base and the height of a
cylinder are 14 cm and 20 cm respectively. What is the volume of the cylinder? .
a cylinder = pr27
= 22/7 x 14 x 14 x 20 = 12320 cm3
A sphere of radius 7 cm is cut into two equal
halves. What is the volume of each of the halves? .
Each half is a hemisphere of radius 7 cm. .
\ Volume of each of the halves
= pr3 = (7)3
= = = 718cu.cm