"... had been devised by ... and was likely brought to by... ... in 1580... This method was based on...\sin A \sin B = \frac{1}{2}[ \cos (A-B)- \cos (A+B) ], \cos A \cos B = \frac{1}{2}[ \cos (A-B)+ \cos (A+B) ].With... a table of sines, these... could... replace multiplications by additions and subtractions, something...Wittich found out, but apparently Werner didn’t realize."