Circle With Center o and Radius r with point P Small 296×320 Medium 592×640 Large 947×1024 Download TIFF Original 2219×2400 | (211.0 KB) Description Circle modeling the earth. O is the center of the earth, r the radius of the earth, and h the height of the point P above the surface; it is required to find the distance from the point P to the horizon at A. Keywords angle, center, circle, Distance, earth, height, Horizon, length, point, radii, radius, surface, triangle, triangles, trig, trigonometry Galleries Trigonometry: Circles Source: Claude Irwin Palmer Library of Practical Electricity: Practical Mathematics For Home Study (New York: McGraw-Hill Book Company, Inc., 1919) 435