In △DEF, shown in the figure below, EG is an altitude, ∠DEF is a right angle,
EF=20 centimeters, and the measure of ∠EDF is 30∘. What is EG, in centimeters?
Approach
When an altitude is drawn in a right triangle, the 2 triangles formed and the orginal triangle will be similar.
All triangles are 30−60−90 special triangles.
The ratios of a 30−60−90 triangle are 1:3:2. For triangle △EGF, the hypotenuse is 20, the short side is 10, and the longer side is 103.