NTA Abhyas JEE Main2020MathematicsCirclePractice
Let A be the centre of the circle x 2 + y 2 - 2 x - 4 y - 20 = 0 . If the tangents at the points B 1,7 and D 4 , - 2 on the circle meet at the point C , then the perimeter of the quadrilateral A B C D is
Options
- A60 units
- B20 units
- C40 units
- D50 units
Correct answer
C. 40 units
Step-by-step solution
The radius of the given circle is 5 = A B = A D Equation of the tangent at B 1,7 is y = 7 and equation of the tangent at D 4 , - 2 is 3 x - 4 y = 20 Point of intersection of y = 7 and 3 x - 4 y = 20 is 16,7 = C Now, A B = A D = 5 & C B = C D = 15 ⇒ The perimeter of the quadrilateral A B C D is equal to 5 + 5 + 15 + 15 = 40 units