A particle executes `SHM` in a straight line. In the first second starting from rest it travels distance a and in the next second it travels distance `a` and in the next second it travels distance `d` in the same direction. The amplitude of `SHM` is :

Explanation

To find the amplitude of the simple harmonic motion (SHM) given the distances traveled in the first three seconds, we can follow these steps:

### Step 1: Understand the problem
A particle in SHM starts from rest and travels distances \( a \), \( a \), and \( d \) in the first, second, and third seconds respectively. We need to find the amplitude \( A \) of the SHM.

### Step 2: Analyze the distances traveled
- In the first second, the distance traveled is \( a \).
- In the second second, the distance traveled is again \( a \).
...