1991 AHSME Problems/Problem 29
Problem
Equilateral triangle has on and on . The triangle is folded along so that vertex now rests at on side . If and then the length of the crease is
Solution
has side length . Let and . Thus, and . Applying Law of Cosines on triangles and using the angles gives and . Applying Law of Cosines once again on triangle using the angle gives so The correct answer is .
See also
1991 AHSME (Problems • Answer Key • Resources) | ||
Preceded by Problem 28 |
Followed by Problem 30 | |
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Geometry