Five circles are created to the maximum possible area in a hexagon, find the ratio of the grey region on the image?

Two parabolas with vertical axes of symmetry share each other's vertex, and are contained between horizontal lines that go through their vertices.

What is the ratio of blue area (intersection) to the grey area in the image?

In a unit square, two quarter circles are drawn, centered at two opposite vertices, What is the area of the oval-shaped region?

7 non-overlapping unit circles are inscribed inside a large circle as shown below. Find the area of the shaded region?

If side lengths of the squares in the diagram are 8, 6 and 4 respectively. Find the area of the grey region?

Two congruent circles of radius 5 cm are drawn in such a way that one is 1 cm below the other . Find the area of red coloured region?