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Home > CCG > Chapter 8 > Lesson 8.2.1 > Problem 8-72


Sandip noticed that when he looked into a mirror that was lying on the ground  feet from him, he could see a clock on the wall. If Sandip’s eyes are inches off the ground, and if the mirror is feet from the wall, how high above the floor is the clock? Include a diagram in your solution.  

Draw a diagram:

2 right triangles share the vertex opposite vertical leg of each, triangle on left, has vertical leg on left, labeled 64 inches, & horizontal leg labeled 8 feet = 96 inches, triangle on right, has vertical leg on right, labeled height, & horizontal leg labeled 10 feet = 120 inches, angles at shared vertex, each has 1 tick mark.

Determine why the two triangles are similar. Remember triangles can be similar by AA, SAS, and SSS similarity theorems.

Set up a proportion. Are your units the same?

Solve the equation.