Q71.If a circle C passing through (4, 0) touches the circle x2 + y2 + 4x −6y −12 = 0 externally at a point (1, −1) , then the radius of the circle C is : (1) 5 (2) 2√5 (3) 4 (4) √57
What This Question Tests
The question combines properties of circles, including external tangency and passing through a point, requiring the use of geometric conditions and circle equations to find the radius of the unknown circle.
Concepts Tested
Formulas Used
(x-h)² + (y-k)² = r²
Distance between centers = r₁ + r₂ (external tangency)
Equation of common tangent at point of contact
📚 NCERT Sections This Tests
2.4 — A Spherical Conductor Of Radius 12 Cm Has A Charge Of 1.6 × 10–7C
Physics Class 11 · Chapter 2
2.4 A spherical conductor of radius 12 cm has a charge of 1.6 × 10–7C distributed uniformly on its surface. What is the electric field (a) inside the sphere (b) just outside the sphere (c) at a point 18 cm from the centre of the sphere?
12.7 — The Radius Of The Innermost Electron Orbit Of A Hydrogen Atom Is
Physics Class 12 · Chapter 12
12.7 The radius of the innermost electron orbit of a hydrogen atom is 5.3×10–11 m. What are the radii of the n = 2 and n =3 orbits?
2.2 — A Regular Hexagon Of Side 10 Cm Has A Charge 5 Mc At Each Of Its
Physics Class 11 · Chapter 2
2.2 A regular hexagon of side 10 cm has a charge 5 mC at each of its vertices. Calculate the potential at the centre of the hexagon.
📋 Question Details
- Chapter
- Circles
- Topic
- Equation of a circle
- Year
- 2013
- Shift
- 22 Apr Online
- Q Number
- Q71
- Type
- MCQ
- NCERT Ref
- Class 11 Mathematics Ch 11: Conic Sections (Circles)
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