Question

Two hikers come to a ravine and want to know how wide it is. They set up two similar triangles as shown in the diagram. How far is it across the ravine?

Answer 1

Answer:

d = 80 ft

Step-by-step explanation:

Start with angle BCA, tan(BCA) = 30/15 so BCA = 63.43 degrees.

BCA = ECD since they are opposite angles.

tan ECD = d/40

40 tan(63.4degrees) = d

d = 80 ft

Alternatively, you can use similar triangles since the angles are the same, BCA = ECD, CED = CAB, and CBA = EDC. In that case use proportions to get 30/15 = d/40 so 2 = d/40 and d = 80.