A particle moves in the plane so that and for

MATHEMATICS · Subjective · AP · Calculus BC · Parametric, Polar, and Vector-Valued Functions · Parametric, Polar, and Vector-Valued Functions

Problem

A particle moves in the plane so that

x(t)=e^{t}\cos t

and

y(t)=e^{t}\sin t

for

-2\pi<t<2\pi

. Determine all open intervals of

t

on which the particle moves upward with respect to

x

, that is, on which

y

is increasing as

x

increases.