Answer:
At the centre
Step-by-step explanation:
To prove the position of the centre of mass, usually we take a strip across the circular disc and call it dy; calculate the length of the strip; calculate the mass per unit area of the disc. And then when we carry out some integral operations using R and -R as the boundaries we will arrive at y_cm = 0 which means the centre y_cm is at the centre of mass of this uniform disc.