The marked region is contained in a region with area \(1-\dfrac{\sqrt{3}}{4}-\dfrac{\pi}{6}\) , see
.
It is half of the complement
of a circle of area \(\dfrac{\pi}{256}\), see
, and a region of area \[\frac{15}{32} - \frac{\sqrt{3}}{4} - \frac{\pi}{6}
+ \frac{255}{256}\arcsin\!\left(\frac{8}{17}\right)\,,\] see
.
We deduce that the area of the marked region is \[
\frac{17}{64}
-\frac{\pi}{512} -\frac{255}{512}\arcsin\!\left(\frac{8}{17}\right)
\,.
\]