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

What is the minimum distance between centers of two circles having radii 5 cm and 3 cm such that exactly three common tangents exist?

This question was previously asked in
SSC CGL 2025 Tier 2 Paper 1 Question Paper (19-Jan-2026)
The correct answer is
8 cm

Circles Geometry: Distance for Three Common Tangents

To determine the minimum distance between the centers of two circles that have exactly three common tangents, we need to understand the relationship between the distance ($d$) between their centers and their radii ($r_1$ and $r_2$).

Condition for Three Common Tangents

Exactly three common tangents exist between two circles when they touch each other externally.

  • When circles touch externally, the distance ($d$) between their centers is equal to the sum of their radii ($r_1 + r_2$).

Calculating Minimum Distance

Given:

  • Radius of the first circle, $r_1 = 5$ cm
  • Radius of the second circle, $r_2 = 3$ cm

For the circles to touch externally, the distance ($d$) between their centers must be:

$d = r_1 + r_2$

Substituting the given radii:

$d = 5 \text{ cm} + 3 \text{ cm}$

$d = 8 \text{ cm}$

Therefore, the minimum distance between the centers of the two circles is 8 cm.

Was this answer helpful?

Similar Questions

  1. If the angles of a triangle are in the ratio of 2:3:4, then the difference of the measure of greatest angle and smallest angle is

  2. In ΔABC, ∠A = 90°, AD ┴ BC and AD = BD = 2 cm. The length of CD is

  3. A and B together can complete a work in 24 days. B alone does 1/3rd part of this work in 12 days. How many days will A alone take to complete the remaining work?

  4. The heights of a cone and a cylinder are equal. The radii of their bases are in the ratio 2:1. The ratio of their volumes is:

  5. In an ornament, the ratio of gold and copper is 3:2. The percentage of gold in the ornament is:

  6. If , \(\sqrt{ 3^{n} } = 2187\) then the value of \( n \) is:

  7. If \(x + \frac{1}{x} = 5\) , then find the value of \(\frac{6x}{ x^{2}  + x +1} \)

  8. In a right-angled triangle if the hypotenuse is 20 cm and the ratio of the other two sides is 4:3, the length of the sides are:

  9. The least number which when divides 37044, gives the result a perfect cube, is:

  10. A man spends in 8 months as much as he earns in 6 months. He saves Rs. 6000 in a year. His average monthly income is:


Important Questions from Geometry

  1. If the angles of a triangle are in the ratio of 2:3:4, then the difference of the measure of greatest angle and smallest angle is

  2. In ΔABC, ∠A = 90°, AD ┴ BC and AD = BD = 2 cm. The length of CD is

  3. How many lines of symmetry does a rectangle have?

  4. The number of diagonals in each face a cube is

  5. Which of the following is/are the geometric figures with the line of symmetry?

    I. Rectangle

    II. Isosceles triangle

Need Expert Advice?
Upcoming Exams
UPSSSC PET
October 25, 2026
SSC JE
November 02, 2026
SSC CPO
November 20, 2026
SSC CHSL
November 30, 2026
Test Series
SSC CGL img
SSC
SSC CGL (Tier I + Tier II) 2026 Mock Test Series - Latest Pattern
2503 Tests 6 Tests Free
7885 Attempts
4.2(906)
English, Hindi

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