A right triangle with sides 3 cm, 4 cm and 5 cm is rotated the side of 3 cm to form a cone. The volume of the cone so formed is:
A. 12$$\pi$$ cm3
B. 15$$\pi$$ cm3
C. 16$$\pi$$ cm3
D. 20$$\pi$$ cm3
Answer: Option A
Solution(By Examveda Team)
$$\eqalign{ & {\text{Clearly}}, \cr & {\text{We have }}r = 3\,{\text{cm}}\,{\text{and}}\,h = 4\,{\text{cm}} \cr & \therefore \,\,\,{\text{Volume}} \cr & = \frac{1}{3}\pi {r^2}h \cr & = \left( {\frac{1}{3} \times \pi \times {3^2} \times 4} \right){\text{c}}{{\text{m}}^3} \cr & = 12\pi \,{\text{c}}{{\text{m}}^3} \cr} $$
This Question Belongs to Arithmetic Ability >> Volume And Surface Area
Seema.. In right triangle : hypotenuse is the longest side which can be 5 cm and base is the shortest side which will be 3 cm, in this way the measurement are being placed
Wrong ans it should be 16pi
yes this is wrong. The height of the cone should be 16cm. The figure is drawn correctly but there is a mistake in the calculation. The correct answer is 16 pi. Pls correct that to avoid further mistakes. Because most students believe in this so you should be very careful about this.
when it is rotated from 3cm than i think so that radius will be 4cm
They have said that to rotate around 3 cm side.
That means to make a cone we have to make a round circle around 3 cm line.
How do we know that 3 will be base & 4 will be height. It can be vice versa leading to 16pie.
Pls suggest