SSC CGL Tier II 12 Jan 2017 Paper 1

Question : 60 of 100

Marks: +1, -0

The height and the total surface area of a right circular cylinder are 4 cm and 8p sq.cm. respectively. The radius of the base of cylinder is

Solution:

(1) Height of cylinder = 4 cm.
Total surface area = 2πr (r + h)
∴ 2πr (r + h) = 8π

⇒ r(r+4)=4

⇒ r^{2}+4 r-4=0

⇒ r= {-4 \± √{16+16}}/{2}

= {-4 \± √{32}}/{2}

= {-4 ± 4√{2}}/{2}

=-2+2 √{2}

because

r≠-2-2√{2}

Note : If

a x^{2}+b x+c=0,

then

x= {-b \±√{b^{2}-4 a c}}/{2 a}

Go to Question:

Prev Question

Next Question