此乃2012年GCT数学考题.
x' = 2tsin|t|/t^2 = 2sin|t|/t,y' = 2tcos|t|/t^2 = 2cos|t|/t,
则 dy/dx = y'/x' = cot|t|,(dy/dx)|t =π/3 = cot|t| = √3/3,选A.
此乃2012年GCT数学考题.
x' = 2tsin|t|/t^2 = 2sin|t|/t,y' = 2tcos|t|/t^2 = 2cos|t|/t,
则 dy/dx = y'/x' = cot|t|,(dy/dx)|t =π/3 = cot|t| = √3/3,选A.