A set of meticulously designed procedures and ingenious methods for calculating the exact values of sine/cosine for 1° and any integer degree has been discovered and constructed. By calculating the sine/cosine values for 3°, and then using the expansion formulas for sine/cosine of triple angles, a univariate cubic equation satisfied by the sine/cosine values of 1° is derived. Subsequently, the exact expressions for sin/cos 1° are determined using Cardano's formula and its discriminant rules. After calculating the exact values of sine/cosine for all integer degrees up to 45° in the form of 3k°, the exact expressions for sine/cosine of all angles in the form of 3k±1° are calculated, and a table of exact sine/cosine values for any integer degree is compiled.
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Hirota's bilinear derivative transformation is a direct method which is more convenient than the inverse scattering transform to deal with a nonlinear partial deferential equation. Based on Hirota's method, the soliton solutions of the modified nonlinear Schrdinger (MNLS) equation under standing wave boundary condition, are obtained; and by simple method of parameter vanishing, the corresponding soliton solutions of the derivative nonlinear Schrdinger (DNLS) equation under constant nonvanishing boundary condition, are gotten, which allows the existence of both bright and dark solitons. The evolution of bright/ dark-soliton solutions in time and space is demonstrated in figures. The results are consistent with what were obtained by the inverse scattering transform.
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