人工智能教程 – 数学基础课程1.1 – 数学分析(一) 25 反向变量替换配方

反向变量替换,配方 sec=1cos tan=sincos\large sec = \frac{1}{cos} \ \ \ tan = \frac{sin}{cos}sec=cos1​ tan=cossin​ csc=1sin cot=cossincsc = \frac{1}{sin} \ \ \ cot = \frac{cos}{sin}csc=sin1​ cot=sincos​ sec2=1+tan2sec^2 = 1+tan^2sec2=1+tan2 tan′=sec2tan’=sec^2tan′=sec2 sec′=sec.tansec’=sec.tansec′=sec