Use app×
Join Bloom Tuition
One on One Online Tuition
JEE MAIN 2025 Foundation Course
NEET 2025 Foundation Course
CLASS 12 FOUNDATION COURSE
CLASS 10 FOUNDATION COURSE
CLASS 9 FOUNDATION COURSE
CLASS 8 FOUNDATION COURSE
0 votes
112 views
in Parabola by (114k points)
closed by
If parabola y2 = 4kx passes through point (-2, 1), then the length of latus rectum is:
1. \(\frac 12\)
2. \(\frac 13\)
3. \(\frac 14\)
4. None of these
5. \(\frac 23\)

1 Answer

0 votes
by (115k points)
selected by
 
Best answer
Correct Answer - Option 1 : \(\frac 12\)

Concept:

The length of the latus rectum of the parabola y2 = 4ax is 4a.

Calculations:

Given, the parabola y2 = 4kx passes through point (-2, 1),

⇒The  point (-2, 1) is satisfying the equation of parabola y2 = 4kx 

⇒ (1)= 4k (-2)

⇒ k = \(\rm \frac {-1}8\)

Now, the length of the latus rectum = 4k

⇒The length of latus rectum = 4(\(\rm \frac {-1}8\))

⇒The length of latus rectum = \(\frac {-1}{2}\)

The length of latus rectum can not be negative.

⇒The length of latus rectum = \(\frac {1}{2}\)

Hence, if parabola y2 = 4kx passes through the point (-2, 1), then the length of the latus rectum is \(\frac {1}{2}\).

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

...