Chords of circle

The sum of the square of the length of all the possible chords intercepted by the line x + y = n, for some n(belongs to N) on the circle x2 + y2 = 4 is what?

6 Answers

62
Lokesh Verma ·

Nikhil.. Try graphs!

It wont fail you :)

1
Nikhil Bajoria ·

Sir, I got the answer as (2√2)2 + (7)2 = 57.

However, the options are 11 or 22 or 33 or 48.

Please help.

62
Lokesh Verma ·

The sum of the square of the length of all the possible chords intercepted by the line x + y = n, for some n(belongs to N) on the circle x2 + y2 = 4 is what?

nikhil, what is the length of the chord when n=0?
and n=1, or n=2??

for other values of n, will it hit the chord

I think you have not understood the question correctly!

1
Nikhil Bajoria ·

For x + y = 1, square of length of chord is 14[points are {-(-1 + √7)/2, (1 + √7)/2)} and { (1 + √7)/2, -(-1 + √7)/2}]

For x + y= 0, square of length of chord is 16.[it is a diameter)

For x + y = 2, square of length of chord is 8[points are (2,0) and (o,2)].

So my answer comes out to be (14 + 16 + 8)=38.

However, the answer is 11 or 22 or 33 or 48. What to do, sir?

62
Lokesh Verma ·

Nikhil

sorry I completely missed this question

see closely.

Is the diameter of the circle 4 or 16?!

1
Nikhil Bajoria ·

sir, the diameter is 2√4=4

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