Concentric Circles With Angle of 1 ° Small 320×294 Medium 640×588 Large 1024×941 Download Tiff Original 2400×2205 | (206.9 KB) Description "If AOB is an angle of 1 ° on the larger circle, it is also 1 ° on the smaller concentric circle, and the length of the arc AB is to the length of the arc CD as to radius OB is to the radius OD; or, arc AB:arc CD = OB:OD." Keywords 1 degree angle, 1°, circle, concentric circles, proportion, proportional Galleries Trigonometry: Circles Source: International Correspondence Schools I.C.S. Reference Library Mathematics (Scranton: International Textbook Company, 1905) Geometry & Trigonometry Pg. 20 Courtesy the private collection of Roy Winkelman