Question

Thales, an ancient Greek mathematician and philosopher, used certain triangles to find the height of unknown objects. He waited for the time of day when the shadow of a meter stick was exactly one meter long. At this exact moment, Thales said the height of the unknown object would also be the same as the length of its shadow. What type of triangle was he using? Explain why this theory works.

Answer 1

He was using an isosceles right triangle.

Both legs of an isosceles triangle are the same length, so knowing that when the shadow of the triangle was the same height as the triangle, then he knew that the shadow of an object would also be the same as it's height.