一起记,最好自己能推下来实在忘了根据sin(a+b)=sinacosb+sinbcosacos(a+b)=cosa^2-cosb^2tan(a+b)=(tana+tanb)/(1-tanatanb)加2π就等于白加,加减π,正余弦都取－,正余切不变sin(a+π)=-sina.加kπ/2(k属于N+),正弦...