Simply Simple

Geometry Level 4

Let A B C ABC be a triangle in which A B = A C AB=AC and let I I be it's in-centre. Suppose B C = 2 A B − A I BC=2AB-AI , then find the value of ∠ B A C \angle BAC in degrees.


The answer is 120.

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Shubhendra Singh by Shubhendra Singh , 20, India

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1 solution

Ahmad Saad
Dec 1, 2015

7 Helpful 0 Interesting 0 Brilliant 0 Confused

Simply brilliant! I did it by splitting it into two right angled triangles and then I used the angle bisector theorem and Pythagoras' Theorem, but this is much more elegant. Thank you for this problem!

Michael Ng - 5 years, 6 months ago

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