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Geometry Level 4

In the figure A G = 2 cm , G B = 12 cm , B E = 3 cm , E C = 10 cm , C F = 4 cm , F A = 11 cm AG=2 \text{ cm},GB=12 \text{ cm},BE=3 \text{ cm}, EC=10 \text{ cm},CF=4 \text{ cm}, FA=11\text{ cm} , If the area of shaded region can be expressed as M G \frac{M}{G} Where both are co-prime to each other, then find M + G M+G .

Note :The answer is not as sweet as M and G.


The answer is 18167773.

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2 solutions

Ahmad Saad
Mar 27, 2016

Nice solution...but can we solve it by any other method?and can you please elaborate that how by menelaus' theorem AP/PE=13/60?

Harshi Singh - 5 years, 2 months ago

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Menelaus' theorem,

Given a triangle ABE, and a transversal line GC that crosses AB, BE and EA at points G, C and P respectively,

then, | (AP/PE)(EC/CB)(BG/GA) | = 1

AP/PE * 10/13 * 12/2 = 1

AP/PE = 13/60

Ahmad Saad - 5 years, 2 months ago

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Thanks and I think This is the generalised form for solving these type of problems

Harshi Singh - 5 years, 2 months ago

Good solution!

Akshay Yadav - 5 years, 2 months ago
Akshay Yadav
Apr 4, 2016

I always kept thinking a way to solve it by similarity and stuff like that, seeing no success in that I finally decided to use coordinate geometry. I assumed B = ( 0 , 0 ) B=(0,0) and C = ( 13 , 0 ) C=(13,0) . Through these two we get A = ( 70 13 , 168 13 ) A=\left(\frac{70}{13},\frac{168}{13}\right) .

Then I found out the points E E , F F and G G . Then I found out the equations for B F BF , C G CG and A E AE . Then their solutions (or intersections as P P , Q Q and R R ). And then the area, of P Q R \bigtriangleup PQR . I had had lost my patience till then but still I tried the answer!

The coordinates are, P = ( 4707 949 , 10080 949 ) P=\left(\frac{4707}{949},\frac{10080}{949}\right) , Q = ( 207 65 , 2016 2015 ) Q=\left(\frac{207}{65},\frac{2016}{2015}\right) and R = ( 6417 611 , 2016 611 ) R=\left(\frac{6417}{611},\frac{2016}{611}\right) .

Very very long and tiring method.

@Harshi Singh did you used the generalized formula to solve the question in the first place?

Akshay Yadav - 5 years, 2 months ago

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My problems are usually based on whatever i study on internet or from some similar resources , One day i was studying unknown theorem's of geometry,Thereby i came to know this theorem and thus posted a problem on it. So, yes at first place i use the formula but now Sir ahmad has shown a more delicate way to solve it........

Harshi Singh - 5 years, 2 months ago

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Yes! I also loved his solution.

Akshay Yadav - 5 years, 2 months ago

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