In an equilateral triangle, the inradius, circumradius, and one of the exradii are in the ratio (a) 2:4:5      (b)  1:2:3          (c) 1:2:4      (d)  2:4:3

Explanation

To solve the problem, we need to find the inradius (r), circumradius (R), and one of the exradii (r1) of an equilateral triangle and express them in a ratio.

### Step-by-Step Solution:

1. **Define the side of the equilateral triangle**:
Let the side of the equilateral triangle be \( a \).

2. **Calculate the area (Δ) of the triangle**:
...