#### Topic: It was tangled in three corners, mathematicians, help

Hello! There is an arc, is set by radius, an initial corner, finite, and a bypass direction - clockwise or against. It is necessary to receive dFi - a difference between a finite and initial corner. It can be both positive, and negative - a sign will specify a bypass direction, i.e. as a result an arc should be set in radius, an initial corner and a corner increment. Tried to subtract from a finite corner initial - does not work. Two corners, 90 and 30, a direction on the hour. 30 - 90 =-60, like. I try on the contrary - should the circle without sector turns out, and it turns out as a result of 90 - 30 = 60, i.e. the same 60, is simple with other sign, and should be 300. Tried corners in 0 - 360, or in-180 - +180, tried to search for addition to 360 - all the same or in half of cases not that quits, or in a quarter. , I can not think. The mathematics after HIGH SCHOOL somehow was not necessary generally, anything any more I do not remember Kick in the necessary direction