Notice that the ramp and the ground are tangents to the circle and they intersect each other at the beginning of the ramp.
15^(∘)
Practice makes perfect
Let's begin by making a diagram that illustrates the given situation.
Our mission is to find m∠ B. To do that, we notice that AB and BC are tangents to the circle and intersect each other in the exterior of it. Therefore, the measure of ∠ B equals one-half the difference of the measures of the intercepted arcs.
From the diagram, we have that mAC=165^(∘). This allows us to calculate the measure of the major arc.
mADC &= 360^(∘) - mAC^(165^(∘))
&= 195^(∘)
Finally, let's substitute the measures of both intercepted arcs to find the angle the ramp makes with the ground.
