Answer:
First blank =

Second blank =

Third blank =

Explanation:
We are given,
The argument to explain the derivation of the formula for the volume of a cone.
According to the explanation, we have,
First blank: It represents the area of the base of the cylinder.
Since, the base of the cylinder is a circle.
And, area of the circle =

Thus, the first blank =

Second blank: It represents the number by which volume of the cylinder is multiplied to obtain the volume of the cone.
Since, we know,
of Volume of cylinder is given by volume of the cone.
Hence, the second blank =

Third blank: It represents the formula for the volume of the cone.
As, Volume of the cone =

Thus, third blank =
