This one turns out to be a pretty straight forward question if you relay on a couple of formulas.
Basically, we are seeking to estimate the area of a circle and to do that we need a radius. There must be a relationship between the radius of the incircle and the area of the equilateral triangle.
Let's start off recalling the formula of the equilateral triangle's area.
A= s^2 (√3/4) (where s is a side of the equilateral triangle)
Now from the above expression we ensue that s= 4 √6
Now we know that the radius of a circle inscribed in an equilateral triangle is equal to the length of the side multiplied by √3/6
From here we just need to plug the values in and solve the equation accordingly which will yield 8(22/7) and the correct answer is D.
Either suffer the pain of discipline, or suffer the pain of regret.
If my posts are helping you show some love awarding a kudos