Calculate the remaining area of a quadrant with two non overlapping half circles

[Aussiebear]

Then there is no need to ask for the HalfCircle1Radius in the function arguments since it's always half the Quadrant radius, in which case the function becomes:

Function CalculateQuadrantRemainingArea(QuadrantRadius As Double) As Double
CalculateQuadrantRemainingArea = QuadrantRadius ^ 2 / 4.583662361
End Function

I'm sorry P45cal but how did you arrive at this figure "4.583662361"?

Never mind I've found how you arrived at this figure:

The constant 4.583662361 was arrived at by pre-calculating the value of 5π72​.
This means the other member's function is a simplified version of our derived formula, specifically tailored for the case where the first half-circle's radius is always half of the quadrant's radius (r1​=R/2).