Plane angle It refers to an angle in 2 dimensional figure like square, triangle, circle etc. There are defined by two types. 1. a plane angle defined by 60 minutes It is an angle notation that is usually used by ordinary people. As shown below, the 60minute method separates the circle into 360 pieces, which is 6times of 60, and then the angle of one piece defines as 1∘. And 1∘ divided by 60 minu..
