Difference between revisions of "2021 AMC 10B Problems/Problem 21"
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Revision as of 00:00, 12 February 2021
A square piece of paper has side length and vertices and in that order. As shown in the figure, the paper is folded so that vertex meets edge at point , and edge at point . Suppose that . What is the perimeter of triangle
double angle tangent to find angle ACE then trig
Assume that E is the midpoint of . Then, and since , . By the Pythagorean Theorem, . It easily follows that our desired perimeter is ~samrocksnature
Video Solution by OmegaLearn (Using Pythagoras Theorem and Similar Triangles)