The shape below is constructed using four semi-circles. It is called a Salinon.

What is the relationship between the area of the shaded region and the area of the circle whose diameter is $AB$?

Mathematical reasoning & proof. Number theory. Circle properties and circle theorems. smartphone. Area - circles, sectors and segments. Manipulating algebraic expressions/formulae. Inequality/inequalities. Making and proving conjectures. Plane shapes and their properties. Regular polygons and circles.