Blackburn's formula does this by sketching the arc of your car's turning capability into a full circle, then using the center of the circle to create the right-angle triangles Pythagoras loved.
Blackburn教授的公式通过对车的弧度和转角能力画圈，利用圆心来设置一个直角三角形。
Next, the center of the pie is erased by drawing a white circle, and another arc is drawn to provide a visual border between the interior circle and the peripheral pie slices.
接下来，将绘制一个白色圆形擦掉饼图的中心，并且绘制另一条弧线来提供内部圆形与外围饼图分区之间的可视边界。
A radian is the Angle subtended by an arc of a circle whose length is just equal to the radius.
一弧度就是长度刚好等于半径的一段圆弧所对的圆心角。
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