Questions about getting and setting scaling in mapwindow6

Hello everyone. I have questions about the scaling calculation in mapwindow6.

// The angle value of 1 radian * The short radius = the length of 1 radian (m)
Double meterperdegree = m_map.layers [0]. dataset. Projection. geographicinfo. Unit. radians * 6354101.943;
// Scale = the length of the displayed radians (converted to pixel values)/the pixel value of the radians in the display area of the screen
Int scale = convert. toint32 (unitmeterconversion () * m_map.envelope.width * 39.3700787 * 100d)/m_map.mapframe.view.width );

Question 1: Why is there a deviation in the unit (m) of the radians obtained using the short radius?
Why is inch converted to pixel fixed as 100 (inchperdot)? Shouldn't it be calculated?
Question 2: How to Use the specified scale to display the current map