S = (a^2 + b^2)^(1/2)
dS d(a^2 + b^2)^(1/2) d(a^2 + b^2)^(1/2) d(a^2 + b^2)
─ = ───────── = ────────── * ───────
dx dx d(a^2 + b^2) dx
1/2
= ────────── * (2a)
(a^2 + b^2)^(1/2)
a*(a^2 + b^2)^(1/2)
= ──────────
a^2 + b^2
應該是這樣吧...如果沒記錯的話XD
--
※ 發信站: 批踢踢實業坊(ptt.cc)
◆ From: 140.114.78.47