To prove that the area of a circle is half the product of its circumference and radius with the help of practical

What level of mathematics is this for? If you're in high school geometry I would suggest one technique, which relies on knowing that the area of a circles is \pi r^2. If you're in a calculus class I would suggest a different approach that derives the value for the area from basic principles.

Area of a circle = A = (pi) * (r ^ 2)
Circumference of a circle = C = 2 * (pi) * r
A = (1/2) * C * r = (1/2) * (2 * (pi) * r ) * r
A = (pi) * (r ^ 2) Q.E.D.

"Q.E.D." stands for "quod erat demonstrandum," which is Latin
for "which was to be demonstrated." The acronym "Q.E.D." is used
often in math textbooks. :)