Reference Angles/Triangles Formed by Angles in Quadrants Small 320×192 Medium 640×384 Large 1024×614 Download Tiff Original 2400×1440 | (165.9 KB) Description Lines drawn to horizontal to form triangle ratios (reference triangles, angles). Keywords angles, quadrants, reference angle, reference triangle, triangles, trig ratios, trigonometric angle, trigonometry Galleries Trigonometry: Angles Source: Claude Irwin Palmer Library of Practical Electricity: Practical Mathematics For Home Study (New York: McGraw-Hill Book Company, Inc., 1919) 405
