The period of revolution(T) of a planet moving round the sun in a circular orbit depends upon the radius (r) of the orbit, mass (M) of the sun and the gravitation constant (G). Then T is proportioni of `r^(a)`. The value of a is

Explanation

To solve the problem of finding the value of \( a \) in the relationship between the period of revolution \( T \) of a planet and the radius \( r \) of its orbit, as well as the mass \( M \) of the sun and the gravitational constant \( G \), we will use dimensional analysis.

### Step-by-Step Solution:

1. **Establish the relationship**:
We assume that the period \( T \) is proportional to \( r^a \), \( M^b \), and \( G^c \). Thus, we can write:
\[
T \propto r^a M^b G^c
...