Three Square Problem

Geometry Level 1

In the image above, have 3 squares A B E F ABEF , D C F G DCFG and C D G H CDGH . Find the sum of the angles α \alpha , β \beta and γ \gamma . Put you answer in degree.


The answer is 90.

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5 solutions

Pietro Pelliconi
Oct 20, 2014

Type on YouTube "The Three Square Geometry Problem - Numberphile"

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ss p - 6 years, 7 months ago
Hussein Khayou
Sep 9, 2016

A F F G = 2 \frac{AF}{FG}=\sqrt{2}

A H A G = 10 5 = 2 \frac{AH}{AG}=\frac{\sqrt{10}}{\sqrt{5}}=\sqrt{2}

F H A F = 2 2 = 2 \frac{FH}{AF}=\frac{2}{\sqrt{2}}=\sqrt{2}

A F H \triangle{AFH} is similar to A F H \triangle{AFH} then F A G ^ = γ \widehat{FAG}=\gamma

β = G A C ^ \beta=\widehat{GAC}

α = F A E ^ \alpha=\widehat{FAE}

α + β + γ = F A E ^ + G A C ^ + F A G ^ = 90 \alpha + \beta +\gamma =\widehat{FAE}+\widehat{GAC}+\widehat{FAG}=90

Ayush Choubey
Nov 26, 2014

\angle AGH = 45 (DIAGONALS BISECT THE ANGLES = 90/2).....

tan \angle AFH= 1/2.....

tan \angle AEH=1/3......

tan[ \angle AFH+ \angle AEH]= tan \angle AFH+tan \angle AEH/1-tan \angle AFH tan \angle AEH} = 1 / 2 + 1 / 3 1 1 / 2 1 / 3 \frac{1/2+1/3}{1-1/2*1/3} = 5 / 6 5 / 6 \frac{5/6}{5/6} = 1........

So \angle AFH+ \angle AEH=45........

SO \angle AGH+ \angle AFH+ \angle AEH = 45 + 45 = 90 \boxed{90}

Jeffrey H.
Nov 11, 2018

Rearrange the triangles as shown. If we let the original square have a side length of x x , we can get the lengths shown by given measurements, the Pythagorean Theorem, or the Distance Formula. Note that the quadrilateral satisfies the converse of Ptolemy's Theorem. Therefore, this quadrilateral is a cyclic quadrilateral, so the opposite angles add to 18 0 180^\circ . This gives α + β + γ + 9 0 = 18 0 \alpha+\beta+\gamma+90^\circ=180^\circ α + β + γ = 9 0 . \alpha+\beta+\gamma=\boxed{90^\circ}.

Rahul Kamble
Nov 10, 2014

Alpha=45 ......angle made by diagonal Tan(beta)=1/2 Tan (gamma)=1/3 Now use property, tan (A+B)=(tanA+tanB) /1-tanAtanB Get the answer

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