arrow
arrow
arrow
The chord of contact of tangents drawn from a point on the circle x² + y² = a² to the circle x² + y² = b² touches the circle x² + y² = c² such thatb
Question

The chord of contact of tangents drawn from a point on the circle x² + y² = a² to the circle x² +
y² = b² touches the circle x² + y² = c² such thatbm=ancp, b^m=a^n c^p,​ where m, n, p, ∈ N. Find the value of
m + n + p + 10.

A.

18

B.

10

C.

14

D.

12

Correct option is C

Given:

The chord of contact of tangents drawn from a point on the circle x² + y² = a²

to the circle x² +y² = b² touches the circle x² + y² = c²

such that bm=ancpb^m=a^n c^p, where m, n, p, ∈ N. 

m + n + p + 10. 

Solution:

Let there is a point P(h, k) on the circlex2+y2=a2. x^2 + y^2 = a^2.​​

(h, k) will satisfy the equationx2+y2=a2 x^2 + y^2 = a^2​.

=>h2+k2=a2 h^2 + k^2 = a^2

​​

The equation of the chord of the contact of tangents drawn from the point P(h, k) to the circlex2+y2=b2 x^2 + y^2 = b^2​ will be

hx+ky=b2hx + ky = b^2​​

The perpendicular distance of this tangent from the center of the circle x2+y2=c2 x^2 + y^2 = c^2 will be equal to the radius of the circle.

b2h2+k2=c\left| \frac{-b^2}{\sqrt{h^2 + k^2}} \right| = c 

b2a=c\left| \frac{-b^2}{a} \right| = c 

b2=acb^2 = ac​​

Comparing it with bm=ancpb^m=a^n c^p​​

=> p = 1, m =2 ,n = 1 

so, ​m + n + p + 10.  =  10+1+1=+2   

                                         =14


Free Tests

Free
Must Attempt

CBT-1 Full Mock Test 1

languageIcon English
  • pdpQsnIcon100 Questions
  • pdpsheetsIcon100 Marks
  • timerIcon90 Mins
languageIcon English
Free
Must Attempt

RRB NTPC Graduate Level PYP (Held on 5 Jun 2025 S1)

languageIcon English
  • pdpQsnIcon100 Questions
  • pdpsheetsIcon100 Marks
  • timerIcon90 Mins
languageIcon English
Free
Must Attempt

CBT-1 General Awareness Section Test 1

languageIcon English
  • pdpQsnIcon40 Questions
  • pdpsheetsIcon30 Marks
  • timerIcon25 Mins
languageIcon English
test-prime-package

Access ‘RRB NTPC’ Mock Tests with

  • 60000+ Mocks and Previous Year Papers
  • Unlimited Re-Attempts
  • Personalised Report Card
  • 500% Refund on Final Selection
  • Largest Community
students-icon
354k+ students have already unlocked exclusive benefits with Test Prime!
Our Plans
Monthsup-arrow