Question

What is the area of the regular polygon? It is a three sided polygon with the apothem of 7m?

Answer 1

That's an equilateral triangle (a three sided regular polygon) with a height of 7 m.

The equilateral triangle bisected along its altitude is the biggest cliche in geometry, the 30/60/90 right triangle, sides in ratio 1:√3:2.  

In this story the apthem is the height, let's call it h, and we'll call the other leg w.  w:h=1:√3 so w = h/√3

The area of the 30/60/90 triangle is wh/2 and the equilateral triangle is two of these so its area Δ is

Δ = wh = h²/√3

We have h = 7m

Δ  = 49/√3  ≈ 28.290163190291665

We could move the radical to the numerator for a high school ready exact answer but I'll just say

Answer: 49/√3 square meters