Ask Questions, Get Answers

Want to ask us a question? Click here
Browse Questions
Home  >>  CBSE XI  >>  Math  >>  Conic Sections
0 votes

If a parabolic reflector is 20 cm in diameter and 5 cm deep, find the focus.

Can you answer this question?

1 Answer

0 votes
The problem can be expressed diagrammatically as follows:
This is a parabola of the form $y^2 = 4ax$, as it opens to the right.
It passes through the point $(10,5) \rightarrow 10^2 = 4 \times a \times 5 \rightarrow 100 = 20a \rightarrow a = 5$
Therefore, the focus $= (a,0) = (5,0)$. This is the mid-point of the diameter.
answered Apr 8, 2014 by balaji.thirumalai

Related questions

Ask Question
student study plans
JEE MAIN, CBSE, AIPMT Mobile and Tablet App
The ultimate mobile app to help you crack your examinations
Get the Android App