Trigonometric Values?

Geometry Level 4

\[\large \ \cos^{2} 73^{\circ} \ + \ \cos^{2} 47^{\circ} \ + \ \cos 73^{\circ} \cos 47^{\circ}\]

If the value of the above expression is equal to \(\dfrac {a}{b}\), where \(a\) and \(b\) are coprime positive integers, find \(a+b\).