Re: [考古] 90年
※ 引述《kusorz (^~^)》之銘言：
: 試求tan^-1(125)+tan^-1(0.008)=?
-1
令 A = tan (125) , 0 < A < π/2
-1
B = tan (0.008) , 0 < B < π/2
則 tanA = 125 , tanB = 0.008
0 < A + B < π
tan(A + B)
tanA + tanB
= ------------------
1 - (tanA)(tanB)
125 + 0.008
= ------------------
1 - (125)(0.008)
125.008 125.008
= --------- = --------- = ∞
1 - 1 0
-1 -1 π
tan (125) + tan (0.008) = A + B = ---
2
--
※ 發信站: 批踢踢實業坊(ptt.cc)
◆ From: 140.119.129.142
討論串 (同標題文章)