Discussion
Two right circular cones of equal curved surface areas have slant heights in the ratio of 3 : 5. Find the ratio of their radii.
Answer: C
The curved surface area of a cone is \( \pi r l \). Equal areas give
\[ \pi r_{1} l_{1} = \pi r_{2} l_{2} \quad\Longrightarrow\quad \frac{r_{1}}{r_{2}} = \frac{l_{2}}{l_{1}} \]
With \( l_{1} : l_{2} = 3 : 5 \):
\[ \frac{r_{1}}{r_{2}} = \frac{5}{3} \quad\Longrightarrow\quad 5 : 3 \]
The radii are in the inverse ratio of the slant heights, since their product is fixed - the cone with the shorter slant must be wider to make up the same area.
No comment is present. Be the first to comment.
Loading…
Post your comment
Please log in or register to post a comment.
Examination Categories
- SSC Exams
- Banking Exams
- Teaching Exams
- Civil Services Exams
- Railways Exams
- Engineering Recruitment Exams
- Defence Exams
- State Government Exams
- Police Exams
- Insurance Exams
- Nursing Exams
- Other Government Exams
- NRA CET
- PG Entrance Exams
- Campus Placement
- MBA Entrance Exams
- CUET and UG Entrance
- Judiciary Exams
- Regulatory Body Exams
- Software Development