Question
Question: The locus of the point of intersection of the tangents to the parabola x<sup>2</sup> – 4x – 8y + 28 ...
The locus of the point of intersection of the tangents to the parabola x2 – 4x – 8y + 28 = 0 which are at right angles is
A
y = 0
B
y = –1
C
x = 1
D
y = 1
Answer
y = 1
Explanation
Solution
Locus of point of intersection of ^ tangent
(i) Directrix
x2 – 4x – 8y + 28 = 0
Ž x2 – 4x = 8y – 28
Ž x2 – 4x + 4 = 8y – 28 + 4
(x – 2)2 = 8(y – 3)
Ž X2 = 8Y
Directrix
Y = – 2
Ž y – 3 = – 2
y = 1