#### Answer

The hill makes an angle of $3.8^{\circ}$ with the horizontal.

#### Work Step by Step

Let $\theta$ be the angle the hill makes with the horizontal.
The car's weight of $2800~lb$ is directed straight down. The force of $186~lb$ is directed up the hill at an angle of $\theta$ above the horizontal.
We can draw a triangle with the $2800~lb$ as the hypotenuse of the triangle and the force of $186~lb$ opposite the angle $\theta$.
We can find $\theta$:
$sin~\theta = \frac{186}{2800}$
$\theta = arcsin(\frac{186}{2800})$
$\theta = 3.8^{\circ}$
The hill makes an angle of $3.8^{\circ}$ with the horizontal.