1. The problem states that the triangle is equilateral, meaning all sides are equal in length. 2. The triangle has a right angle, which is unusual for an equilateral triangle because all angles in an equilateral triangle are 60 degrees. 3. Since the triangle is equilateral, all sides must be equal, so $x = 12$. 4. The length of side $x$ to the nearest tenth is $12.0$.