[Math] how can I find the Side length Two squares inside an equilateral Triangle

geometrytriangles

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Question: Figure shows an equilateral triangle with side length equal to $1$ . Two squares of side length a and $2a$ placed side by side just fit inside the triangle as shown.

Find the exact value of $a$.

Its an Assessment question from edX course "A-Level Mathematics Course 1" and I am supposed to use skills that I learnt in Indices and surds,Inequalities and The Factor Theorem.

I have tried finding the height of triangle and then use similar triangles to find the right triangle length still No luck.

I am just looking for food for thought or very small hints thats all.

Best Answer

From the leftmost right triangle, $$ \frac{a}{x} = \tan(60°) \implies a = \sqrt{3}x $$ From the rightmost right triangle $$ \frac{2a}{1-3a-x} = \frac{a}{x} \\ a = \frac{3-\sqrt{3}}{6} \approx 0.211 $$