What's the height of the tree?

Question

Use similar triangles to solve. A person who is 5 feet tall is standing 117 feet from the base of a tree, and the tree casts a 126 foot shadow. The person's is 9 feet in length. What is the height of the tree?

Answer 1

I'm not sure why we would need to use similar triangles.

This looks like a simple ratio problem...

Tree height is to shadow length as person height is to shadow length..

h_t/s_t = h_p/s_p

 

h_t/126 = 5/9

Cross multiply

9h_t = 5(126)

h_t = 630/9

h_t = 70 ft tall