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 4 of 8.
Madhavi said:
9 years ago
We take 4 height because by using Pythagarous theorem the right angled triangle must want to satisfy the side1^2 + side2^2 =hupotenuous^2.
3^2 + 4^2 = 5^2.
25 = 25.
That's why here we take 4cm has a height.
Suppose if we take height has 5cm.
Then,
3^2 + 5^2! = 4^2.
3^2 + 4^2 = 5^2.
25 = 25.
That's why here we take 4cm has a height.
Suppose if we take height has 5cm.
Then,
3^2 + 5^2! = 4^2.
Aakriti said:
9 years ago
1. A triangle with these dimensions doesn't form a cone.
2. Even if it does then the length of the side rotated would be the circumference of the base of the figure and not the radius.
2. Even if it does then the length of the side rotated would be the circumference of the base of the figure and not the radius.
Kirti said:
9 years ago
If we rotate 3cm side won't 3cm be the circumference of its base.
Vikash said:
9 years ago
According to me, the language of the question is wrong. Because if it is rotated by side 3cm, its radius will never be 3cm, if anybody visualizes it?
Shivang said:
9 years ago
The question is incomplete, it is not mentioned that the 3 cm is the base. And if it is then cone thus formed has symmetry about x-axis with height 3cm.
Sateesh kumar Routhu said:
9 years ago
Hello friends,
3, 4, 5 are the sides and hypotenus of the right angle triangle, i.e. root of 3^2 + 4^2 = 5, in this we can take either 3, 4 or 4, 3 as sides and 5 as a hypotenus. Then we take radious and height of the cone are r = 3, h = 4, or r = 4, h = 3.
We are able to form two cones of different sizes with same area and volume. i.e volume is 12 pi cm^3.
3, 4, 5 are the sides and hypotenus of the right angle triangle, i.e. root of 3^2 + 4^2 = 5, in this we can take either 3, 4 or 4, 3 as sides and 5 as a hypotenus. Then we take radious and height of the cone are r = 3, h = 4, or r = 4, h = 3.
We are able to form two cones of different sizes with same area and volume. i.e volume is 12 pi cm^3.
Anil sarode said:
9 years ago
You are absolutely right @Rohit.
LAWRENCE said:
9 years ago
How can 3 be the radius since it's rotated?
Mia khalifa said:
9 years ago
Why the 3 cm is taken as the radius?
Archana said:
9 years ago
How you take 3cm for the base?
Please, Explain.
Please, Explain.
Post your comments here:
Quick links
Quantitative Aptitude
Verbal (English)
Reasoning
Programming
Interview
Placement Papers