In trig diagrams, what is the symbolism of the lettering?
Generally, capital letters represent points or vertices, small letters represent sides or lengths, and Greek letters represent measures of angles. However, sometimes textbook authors use capital letters to represent vertices and the measure of the angle at that vertex, e.g., A=80° means the measure of angle at vertex A is 80°. Actually they should write, A=80°, where means the measure of the angle. I will use either convention. The most common Greek letters used in trig are = alpha (“al-fah”), = beta (“bay-tah”), = gamma (“gam-mah”), = theta (“thay-tah”), and = phi (“fee”, not “fie”!). In a standard triangle, is the angle at vertex A across from side a, is the angle at vertex B across from side b, and is the angle at vertex C across from side c. In a standard right triangle, = 90°, and c is the hypotenuse.
