Question

.高数题 已知函数z=(1/3)ln(x-y),x=sect,y=3 sint 求（dz/dt) | t=π

Answer 1

z=(1/3)ln(sect-3sint)

dz/dt=(1/3)(secttant-3cost)/(sect-3sint)

t=π

dz/dt=(1/3)(3)/(1）=1