JEE Main20205 Sep 2020Evening ShiftMathematicsCircleActual
If the length of the chord of the circle, x 2 + y 2 = r 2 ( r > 0 ) along the line, y - 2 x = 3 is r , then r 2 is equal to:
Options
- A9 5
- B12
- C24 5
- D12 5
Correct answer
D. 12 5
Step-by-step solution
A B = r , A D = r 2 CD = rsin 60 ° = 3 r 2 ⇒ 0 + 0 - 3 1 2 + 2 2 = 3 r 2 ⇒ r = 2 3 5 ⇒ r 2 = 12 5