Use app×
QUIZARD
QUIZARD
JEE MAIN 2026 Crash Course
NEET 2026 Crash Course
CLASS 12 FOUNDATION COURSE
CLASS 10 FOUNDATION COURSE
CLASS 9 FOUNDATION COURSE
CLASS 8 FOUNDATION COURSE
0 votes
83 views
in Parabola by (95.5k points)
closed by
The angle between the tangents drawn from the point `(1,4)` to the parabola `y^2=4x` is
A. `(pi)/(6)`
B. `(pi)/(4)`
C. `(pi)/(3)`
D. `(pi)/(2)`

1 Answer

0 votes
by (94.8k points)
selected by
 
Best answer
Correct Answer - C
We know tangents to `y^(2) = 4 ax` is `y = mx + (1)/(m)`
`:.` Tangent to `y^(2) = 4x` is `y = mx + (1)/(m)`
Since tangent passes through (1,4)
`:. 4 = m + (1)/(m)`
`implies m^(2) - 4m = 4` (whose roots are `m_(1)` and `m_(2)`)
`:. m_(1) + m_(2) = 4` and `m_(1) m_(2) = 1`
and `|m_(1) - m_(2)| = sqrt((m_(1) + m_(2))^(2) - 4m_(1)m_(2))`
`= sqrt(12) = 2 sqrt(3)`
Thus, angle between tangents
`tan theta = |(m_(2) - m_(1))/(1 + m_(1) m_(2))| = (2 sqrt(3))/(1 + 1) = sqrt(3) implies theta = (pi)/(3)`

Welcome to Sarthaks eConnect: A unique platform where students can interact with teachers/experts/students to get solutions to their queries. Students (upto class 10+2) preparing for All Government Exams, CBSE Board Exam, ICSE Board Exam, State Board Exam, JEE (Mains+Advance) and NEET can ask questions from any subject and get quick answers by subject teachers/ experts/mentors/students.

Categories

...