Chapter Test
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Use that you have two similar triangles.
Height: 140 feet
Why This Works: See solution.
Let's make a diagram illustrating the situation.
h/5.6=100/4 ⇔ h=140 The Unisphere is 140 feet high.
A light ray that hits a mirror is reflected. The angle between the reflected ray and a line perpendicular to the surface is the same as that between the line and the incoming ray, but on the other side of the line.
The angle measures of θ_i and θ_r are equal and both are complementary to the angles between the ray and the mirror. Therefore, we know that the angles between the ray and the mirror must be congruent.
For the method to work we need to have two triangles that are similar. Two triangles are similar if they have two congruent angles. Let's recall the other pair of congruent angles.
These angles are defined by the plane of the mirror and they are congruent only if the mirror is horizontal. The method works because the mirror lies horizontally.