What is the area of the marked triangle?



The marked triangle is a right triangle.
Its legs have length \(\dfrac{1}{2}\) and \(\dfrac{\sqrt{3}}{2}\) respectively.
Hence its area is \[\dfrac{1}{2}\cdot \dfrac{\sqrt{3}}{2}\cdot\dfrac{1}{2}=\dfrac{\sqrt{3}}{8}\,.\]