Sliced Triangle Areas

Geometry Level 4

Medians AD and BE of triangle ABC intersect at P . A line through P parallel to AB meets AC and BC at M and N , respectively. The ratio of the area of MNC to the area of ABC can be written as m n \frac{m}{n} , where m and n are positive coprime integers. Find m + n m+n .


The answer is 13.

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2 solutions

Faraz Masroor
Jan 4, 2014

MPN is parallel to AB, and P is the centroid of triangle ABC: CP intersects AB at F, the midpoint of AB. It is known that CP/PF=2: The medians divide the centroid in a 2:1 ratio. So triangle CMN is similar to CAB with ratio 2:3, so the ratio of their areas is 4/9. 4+9=13.

mine solution was exactly the same.

Eloy Machado - 7 years, 2 months ago

It is a simple example. Rating 3 is high!!

Niranjan Khanderia - 7 years, 1 month ago
Maharnab Mitra
Apr 10, 2014

Well.............. this solution is for the lazy ones, like me!

Assume the triangle to be an equilateral one. Draw the diagram as in the question. Find the ratio of the sides. Then square it to get the answer.

If only the answer is required, this method is the fastest; otherwise...................... :-(

My process is same.

Arghyanil Dey - 7 years, 1 month ago

Did the same

Aditya Chauhan - 5 years, 7 months ago

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