12.设曲线的极坐标方程为 rho =dfrac (1)(pi )(1-cos theta ), 求曲线在 theta =dfrac (pi )(2) 处的切线方程.

[题目]求曲线 =cos x 上点 (dfrac (pi )(3),dfrac (1)(2)) 处的切线方程-|||-和法线方程.

13.求曲线 =cos x 上点 (dfrac (pi )(3),dfrac (1)(2)) 处的切线方程和法线方程.

13.求曲线 =cos x 上点 (dfrac (pi )(3),dfrac (1)(2)) 处的切线方程和法线方程.

__ [例28] (1997,数一)对数螺线 rho =(e)^theta 在点 (rho ,theta )=((e)^n/2,dfrac (pi )(2))

[题目]求曲线 =cos x 在 (dfrac (pi )(3),dfrac (1)(2)) 处的切线方-|||-程.

[题目]求曲线 =cos x 在 (dfrac (pi )(3),dfrac (1)(2)) 处的切线方-|||-程.

求曲线 =t-sin t, =1-cos t =4sin dfrac (t)(2) 在点 (dfrac (pi )(2)-1,1,2sqrt (2)) 处的切线

[题目]求曲线 =sin x 在 =dfrac (pi )(4) 处的切线方程.

(B) sqrt (dfrac {1cos theta )(g)} _ (C) pi sqrt (dfrac {1)(8)} . (D) pi sqrt (df

当theta =dfrac (pi )(3)时，theta =dfrac (pi )(3)______，theta =dfrac (pi )(3)______，