+2668 \(\Delta OCD\) is an isosceles triangle, with \(OC\) and \(OD\) both equal to \(5\).
Label the midpoint of \(CD\) as \(B\). Draw a line connecting \(O\) to \(B\). You have a 60-30-90 triangle, where the hypotenuse is \(5\). This means that \(OB\) is \(2.5\). Using the Pythagorean theorem, you find that \(CB\) is \(\sqrt{18.75}\), which means that \(CD\) is \(2\sqrt{18.75}\), which can be simplified to \(\color{purple} 5\sqrt3\).
