微積分『斜率』

dy/dx

= [(dr/dθ)sinθ + rcosθ]/[(dr/dθ)cosθ - rsinθ]

= [asinθ + aθcosθ]/[acosθ - aθsinθ]

= [sinθ + θcosθ]/[cosθ - θsinθ]

= (1 + 0)/(0 - π/2)

= -2/π




2011-05-28 23:17:25 補充：
Thank you for linch

提示y=rsinθ, x=rcosθ

r = f(θ)

dy/dx
= (dy/dθ) / (dx/dθ)
= [d/dθ (r sinθ)] / [d/dθ (r cosθ)]
= [ (dr/dθ) * sin θ + r cosθ] / [ (dr/dθ) * cosθ - r sinθ ]

請問myisland大：

[(dr/dθ)sinθ + rcosθ]/[(dr/dθ)cosθ - rsinθ]

這行我實在不懂

麻煩講解一下

謝謝