What is there to investigate? Do you want to prove the equality? Do you want to formulate a partial product and see if it converges?
You can define a circle to be a regular polygon with an infinite number of sides. We can define as the circumference of a circle of diameter equal to 1 unit. Therefore, we can get an approximation for by evaluating the perimeter of said regular polygon.
Some algebraic manipulation of this will give the result you are trying to prove.