3.(2 points) Estimate $\frac{d}{dt}[f(c(t))]|_{P}$ where $P(-1, 1)$, $c(t)$, $c'(P)$ are indicated, and the contour lines for $f$ are $f = 1, 2, 3, 4, 5, 6, 7, 8$ as they radiate out from the origin. (Hint: Estimate $\nabla f(P)$ from the graphic and then use that in a relevant calculation. Recall $|\nabla f(P)| = D_u f(P)$ where $u$ is a unit vector in the direction of $\nabla f(P)$)