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# If _{1} & _{2} are length of segments of focal chord of parabola y^{2} = 4ax than harmonic mean of _{1} & _{2} is equal to

- 4a
- 3a
- 2a
- a

## The correct answer is: 2a

### To find the harmonic mean of the segments of a focal chord.

Coordinates of focal chord

A=

B=

Harmonic mean =

Therefore, harmonic mean of the segments of a focal chord is 2a

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