Shades and shadows, with applications to architectural details, and exercises in drawing them with the brush and pen .. (1912)
Ware, William R. (William Robert), 1832-1915 · Scranton, International Textbook Company · leaf 89
radius of the circle beingtaken as 1, the length of the lines gives the true value of these ratios.From this figure we obtain these three equations: Sin* + Cos = 1; Sec - Tan = 1; Cosec - Cot = 1. 41- Since a and b are both smaller than h, the Sine and Cosine are always proper fractions, being… … TRIGONOMETRICAL TERMS 79 4^. It follows that if, for any angle, any one of the six ratios is known, the other five can be obtainedfrom it. For one of the five is the reciprocal of the given ratio, and the other four can be deduced atonce from these two by means of the three equations just given.…
Shades and shadows
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