Spherical pi

is the ratio between length of a circumference of a circle to the length of its diameter. What is for a circle on the surface of a sphere?

Drag the slider on the right to make b=0. What is value of for that circle (the ratio C/D)?

What quantity does represent in the figure?

Drag the slider on the right to make b=0.5. What is the value of for that circle?

Continuing dragging the slider...how does the value of b vary with the value of ?

What is the limit of as the radius of a spherical circle approaches 0?