NTA Abhyas JEE Main2020MathematicsParabolaPractice
Let the tangents at points P and R on the parabola y = x 2 intersects at T . Tangent at point Q (lies in between the points P and R ) on the parabola intersect P T and R T at A and B respectively. The value of T A T P + T B T R is
Options
- A1 2
- B1
- C2
- D4
Correct answer
B. 1
Step-by-step solution
Let, P = t 1 , t 1 2 ,   Q = t 2 , t 2 2   &   R = t 3 , t 3 2 ⇒ T A T P = t 1 + t 3 2 - t 1 + t 2 2 t 1 + t 3 2 - t 1 = t 3 - t 2 t 3 - t 1 and T B T R = t 1 - t 2 t 1 - t 3 = t 2 - t 1 t 3 - t 1 ⇒ T A T P + T B T R = t 3 - t 2 t 3 - t 1 + t 2 - t 1 t 3 - t 1 = t 3 - t 1 t 3 - t 1 = 1