A Sangaku-like Puzzle from Japan

Consider the right-angled triangle on the bottom right. The opposite side is 1 as it’s the unit length of the square. Using the tangent function, we find the length of the adjacent side of the triangle.  Therefore, we can sum up the three segments to find the side length of the equilateral triangle. So how do we show that the area of the outer triangle is about twenty times that of the inner triangle? Notice that the inner triangle is in fact an equilateral triangle with side length 1. <a href="https://medium.com/intuition/a-sangaku-like-puzzle-from-japan-627b9151892d">Click Here</a>