NTA Abhyas JEE Main2020MathematicsCirclePractice
Let two circles having radii r 1 and r 2 are orthogonal to each other. If the length of their common chord is k times the square root of harmonic mean between the squares of their radii, then k 4 is equal to
Options
- A13
- B7
- C4
- D2
Correct answer
C. 4
Step-by-step solution
Area of Δ A B C = 1 2 r 1 r 2 = 1 2 l 2 r 1 2 + r 2 2 ⇒ l = 2 r 1 r 2 r 1 2 + r 2 2 ⇒ l = 2 2 r 1 2 r 2 2 r 1 2 + r 2 2 ⇒ k = 2 ⇒ k 4 = 4