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Geometry Difficulty 4.9 AIME Find the answer

A right triangle and a circle are drawn such that the circle is tangent to the legs of the right triangle. The circle cuts the hypotenuse into three segments of lengths 1,24 , and 3 , and the segment of length 24 is a chord of the circle. Compute the area of the triangle.

A number or a short expression. Spacing and $ signs are ignored.

Solution

Let the triangle be ABC\triangle A B C, with ACA C as the hypotenuse, and let D,E,F,GD, E, F, G be on sides AB,BC,ACA B, B C, A C, ACA C, respectively, such that they all lie on the circle. We have AG=1,GF=24A G=1, G F=24, and FC=3F C=3. By power of a point, we have AD=AGAF=1(1+24)=5CE=CFCG=3(3+24)=9\begin{aligned} & A D=\sqrt{A G \cdot A F}=\sqrt{1(1+24)}=5 \\ & C E=\sqrt{C F \cdot C G}=\sqrt{3(3+24)}=9 \end{aligned} Now, let BD=BE=xB D=B E=x. By the Pythagorean Theorem, we get that (x+5)2+(x+9)2=282(x+5)2+(x+9)2((x+9)(x+5))2=282422(x+5)(x+9)=768(x+5)(x+9)=384\begin{aligned} (x+5)^{2}+(x+9)^{2} & =28^{2} \\ (x+5)^{2}+(x+9)^{2}-((x+9)-(x+5))^{2} & =28^{2}-4^{2} \\ 2(x+5)(x+9) & =768 \\ (x+5)(x+9) & =384 \end{aligned} The area of ABC\triangle A B C is 12(x+5)(x+9)=12384=192\frac{1}{2}(x+5)(x+9)=\frac{1}{2} \cdot 384=192.

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