Analysis and Approaches for IBDP Maths Ebook 1 | Page 139

Front Page
45
Paper 2 Section A – Formulae of areas and volumes
12
Example
The area of a circle is equal to
2
12 cm .
(a)
Find the radius of the circle.
This circle is the base of a solid cylinder of height 20 cm.
[2]
(b)
(c)
Write down the volume of the solid cylinder.
Find the total surface area of the solid cylinder.
[1]
[3]
Solution
(a)
(b)
(c)
2
�r
� 12
(M1) for valid approach
r �
12
�
r � 1.954410048
r � 1.95 cm A1 N2
3
240 cm A1 N1
The total surface area
2
�2�r
� 2�rh
(M1) for valid approach
2
�2 �(1.954410048) � 2 �(1.954410048)(20)
(A1) for substitution
� 269.59841
2
� 270 cm
A1 N3
[2]
[1]
[3]
www.seprodstore.com
131