If `b\ a n d\ c` are lengths of the segments of any focal chord of the parabola `y^2=4a x ,` then write the length of its latus rectum.

Explanation

To find the length of the latus rectum of the parabola \( y^2 = 4ax \) given the lengths of the segments \( b \) and \( c \) of any focal chord, we can follow these steps:

### Step-by-Step Solution:

1. **Understanding the Focal Chord**:
- A focal chord of the parabola \( y^2 = 4ax \) is a line segment that passes through the focus of the parabola and has its endpoints on the parabola. Let's denote the lengths of the segments of the focal chord as \( PS = b \) and \( QS = c \).

2. **Using the Property of Harmonic Mean**:
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