tan(A+B) = (tanA+tanB) / (1-tanA * tanB) = -1从而得到:tanA+tanB = tanA * tanB -1tan(A+B) = (tanA+tanB) / (1-tanA * tanB) = -1从而得到:tanA+tanB = tanA * tanB -1不明白为什么要-1

问题描述:

tan(A+B) = (tanA+tanB) / (1-tanA * tanB) = -1从而得到:tanA+tanB = tanA * tanB -1
tan(A+B) = (tanA+tanB) / (1-tanA * tanB) = -1
从而得到:
tanA+tanB = tanA * tanB -1
不明白为什么要-1

(tanA tanB) / (1-tanA * tanB) = -1
[ (tanA tanB) / (1-tanA * tanB) ](1-tanA * tanB) = -1 (1-tanA * tanB)
(tanA tanB) = -1+tanA * tanB
tanA tanB =tanA * tanB -1

tan(A+B) = (tanA+tanB) / (1-tanA * tanB) = -1
tanA+tanB = (tanA * tanB+1)*(-1)
= tanA * tanB -1
-1是前面1和后面(-1)相乘得来的。

(tanA+tanB) / (1-tanA * tanB) = -1两边同乘以 (1-tanA * tanB),等式两边就为(tanA+tanB)= - (1-tanA * tanB),“-“(1-tanA * tanB)注意这个外面有一个负号打开括号后(tanA+tanB)= - (1-tanA * tanB)=tanA * tanB-1...