Aptitude - Volume and Surface Area - Discussion
Discussion Forum : Volume and Surface Area - General Questions (Q.No. 1)
1.
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:
12
cm3
cm315 cm3
cm316 cm3
cm320 cm3
cm3Answer: Option
Explanation:
Clearly, we have r = 3 cm and h = 4 cm.
 Volume = |
1 | r2h = |
 |
1 | x x 32 x 4 |
 cm3 |
= 12 cm3. |
| 3 | 3 |
Video Explanation: https://youtu.be/Njsid2mVwUY
Discussion:
77 comments Page 3 of 8.
King said:
1 decade ago
The Triangle is rotated about the side 3 so it should be the height and the radius should be 4 and According to volume formula to cone its (1/3)*pi*r*r*h in should be 16*pi.
Rohit said:
1 decade ago
The only possible explanation is that it is rotated about, not revolved about.
If 5th rotates it means it runs around a fixed center. It rotates about 3 cm side means the 3 cm side is rotating.
If 5th rotates it means it runs around a fixed center. It rotates about 3 cm side means the 3 cm side is rotating.
Nameera khan said:
1 decade ago
How can we know the height is 4 its not given even it can be 5 also did not understand please explain?
Khushi said:
1 decade ago
As it is mentioned that the triangle is rotated to the side 3 cm. That's the reason it has become the radius of the so formed cone. It has nothing to do with whether it (3 cm side) is considered the base or the height of the triangle!
Prabhu said:
1 decade ago
If it is rotated along the side with 3cm then how could radius be 3cm?
Swati said:
1 decade ago
Anyone solve this last step of questions?
My answer is not coming 12. I think wrong answer.
My answer is not coming 12. I think wrong answer.
Kanwar Pal Singh said:
1 decade ago
@Swati.
I think you are solving with value of "pi". Otherwise the calculation shit is so simple.
I think you are solving with value of "pi". Otherwise the calculation shit is so simple.
Sravanthi said:
10 years ago
It is not mentioned that 3 is base and 4 is height. Why can't 3 be height and 4 be base? please explain.
Vish said:
10 years ago
Guys, they said triangle is rotated the 3 cm side to form a cone. So the only way the cone can b formed from a right angle triangle is by rotating base and its 3 cm in this case!
Pankaj Dhariwal said:
10 years ago
I can't understand. In this question where we use 5cm. Please explain.
Post your comments here:
Quick links
Quantitative Aptitude
Verbal (English)
Reasoning
Programming
Interview
Placement Papers