function to calculate arc length
static double arcLength ( double diameter , double angle ) { double pi = 22.0 / 7.0 ; double arc ; if ( angle >= 360 ) { Console . WriteLine ( " Angle ▁ cannot " + " ▁ be ▁ formed " ) ; return 0 ; } else { arc = ( pi * diameter ) * ( angle / 360.0 ) ; return arc ; } }