To find the measure of the fourth angle \(f\) in a quadrilateral, we need to use the fact that the sum of the interior angles of a quadrilateral is always \(360^{\circ}\).
Given the angles of the quadrilateral are \(100^{\circ}, 50^{\circ}, 100^{\circ}\), and \(f\), we can set up the equation:
\[
100^{\circ} + 50^{\circ} + 100^{\circ} + f = 360^{\circ}
\]
First, add the known angles:
\[
100^{\circ} + 50^{\circ} + 100^{\circ} = 250^{\circ}
\]
Now, substitute this sum back into the equation:
\[
250^{\circ} + f = 360^{\circ}
\]
To find \(f\), subtract \(250^{\circ}\) from \(360^{\circ}\):
\[
f = 360^{\circ} - 250^{\circ} = 110^{\circ}
\]
Therefore, the measure of the fourth angle \(f\) is \(110^{\circ}\).
\[
f = 110^{\circ}
\]