All Exams Test series for 1 year @ ₹349 only
Question

Using $\pi = \frac{22}{7}$, find the lateral surface area of a right circular cone whose diameter of the circular base is 8 cm and whose slant height is 14 cm.

This question was previously asked in
RRB NTPC 2019 CBT 1 Question Paper (8-Mar-2021) (Shift 2)
The correct answer is
176 cm²

Finding the Lateral Surface Area of a Cone

This solution explains how to calculate the lateral surface area of a right circular cone using the given diameter and slant height.

Given Information:

  • Diameter of the base, $d = 8$ cm
  • Slant height, $l = 14$ cm
  • Value of $\pi = \frac{22}{7}$

Step 1: Determine the Radius

The radius ($r$) of the circular base is half its diameter ($d$).

Calculation: $r = \frac{d}{2} = \frac{8 \text{ cm}}{2} = 4 \text{ cm}$

Step 2: Calculate Lateral Surface Area (LSA)

The formula for the lateral surface area of a right circular cone is:

$LSA = \pi \times r \times l$

Substitute the known values into the formula:

$LSA = \frac{22}{7} \times 4 \text{ cm} \times 14 \text{ cm}$

Perform the multiplication:

$LSA = 22 \times 4 \text{ cm} \times \frac{14}{7} \text{ cm}$

Simplify by dividing 14 by 7:

$LSA = 22 \times 4 \text{ cm} \times 2 \text{ cm}$

Continue multiplying:

$LSA = 88 \text{ cm} \times 2 \text{ cm}$

$LSA = 176 \text{ cm}^2$

Result

The calculated lateral surface area of the cone is $176 \text{ cm}^2$.

Was this answer helpful?

Similar Questions

  1. What is the ratio of volumes of two spheres where the curved surface areas are in the ratio of $1 : 4$?
  2. Five solid cubes, each of volume $39304 \text{ cm}^3$, are joined end to end to form a cuboid. What is the lateral surface area (in $\text{cm}^2$) of the cuboid?
  3. What is the surface area of a sphere of radius 8 cm? (use $\pi = 3.14$)
  4. The ratio of the volumes of two cubes is 64 : 1331. What is the ratio of their total surface areas?
  5. The diameter of a hemisphere is 7 cm. What will its total surface area be?
  6. The diameters of the bases of two cones are equal. If their slant heights are in the ratio of 3 : 4, then what will the ratio of their curved surface areas be?
  7. A cube of volume 324 cm$^3$ is molded into a cuboid whose length, width and height are in the ratio $3 : 2 : 2$. Find the length of the cuboid.
  8. An aquarium is in the form of a cuboid whose external measures are $80 \text{ cm} \times 30 \text{ cm} \times 40 \text{ cm}$. The base, side faces and back face are to be covered with a coloured paper. Find the area of the paper needed?
  9. A godown is in the form of a cuboid of measures $60 \text{ m} \times 40 \text{ m} \times 30 \text{ m}$. How many cuboidal boxes can be stored in it if the volume of one box is $0.8 \text{ m}^3$?
  10. Find the number of bricks measuring 25 cm in length, 5 cm in breadth and 20 cm in height for a wall 40 m long, 80 cm broad and 6 m in height.

Important Questions from 3-D Mensuration

  1. Find the total surface area of a closed cylinder having a base radius of 70 m and a height of 110 m. [Use π = \(22\over7\)]

  2. The curved surface area of a cylinder is half of its total surface area. If its height is 195 cm, then find its diameter (in cm).
  3. The diameter of the base and slant height of a right circular cone are 30 cm and 113 cm, respectively. Find the volume (in cm³) of the given cone.
    (Use $\pi = \frac{22}{7}$)

  4. A cylindrical rod has an curved surface area of $4,900 \text{ cm}^2$. If the length of the rod is 97 cm, then the radius (in cm) of the rod, correct to two places of decimal, is:
    Take $\pi = \frac{22}{7}$
  5. The volume (in $m^3$) of a cube, each of whose edges is 42 m, is:
Need Expert Advice?
Upcoming Exams
RRB JE
October 27, 2026
RRB ALP
November 03, 2026
Test Series
RRB NTPC img
Railways
RRB NTPC Under Graduate 2026 New Mock Test Series
1612 Tests 1 Tests Free
687 Attempts
4.3(510)
English, Hindi, Telugu +7 More
More Questions from RRB NTPC

Start Your Preparation with Prepp Mobile App

Download the app from Google Play & App Store
Download the app from Google Play & App Store
Prepp Mobile App