Archimedean Spiral built by parametric equations[br]An Archimedean Spiral is also known as an arithmetic spiral[br]since there is a constant separation distance on successive turnings of the spiral.[br]It is the trace of a point moving away from a starting point with a constant speed [br]along a line which rotates with constant angular velocity.[br]In the formulas used here, b t cos(t + a), b t sin(t + a),[br]b controls the “tightness” of the spiral,[br]a changes its orientation, while t is the parameter.[br]The slider N controls how many turnings there are.