Stores the numerator and the denominator to find angle A
var numerator = a * a + d * d - b * b - c * c var denominator = 2 * ( a * b + c * d ) var x = numerator / denominator document . write ( " " , Math . round ( ( ( Math . acos ( x ) * 180 ) / 3.141592 ) * 100 ) / 100.0 , " " ) ; document . write ( " " ) ;