# A Tricky Semicircle

**Geometry**Level 2

A semi-circle is inscribed within an equilateral triangle such that the diameter of the semi-circle is centred on one side of the triangle and the arc is tangent to the other two sides. If each side of the triangle is of length 4 cm, then what is the diameter of the semi-circle (in cm)?

Give your answer to 3 decimal places.