Easy, ruins

Geometry Level 3

Given that the number inside each region of the triangle is the area of that region, find the area of A E O . AEO.


The answer is 56.

This section requires Javascript.
You are seeing this because something didn't load right. We suggest you, (a) try refreshing the page, (b) enabling javascript if it is disabled on your browser and, finally, (c) loading the non-javascript version of this page . We're sorry about the hassle.

1 solution

Let y y be the area of A E O \triangle AEO and a a be the area of C O D \triangle COD . Recall that the areas of triangles with equal altitudes are proportional to the bases of the triangles. We have

D C D B = A A D C A A D B = A O D C A O D B \dfrac{DC}{DB}=\dfrac{A_{ADC}}{A_{ADB}}=\dfrac{A_{ODC}}{A_{ODB}}

84 + a + y 40 + 30 + 35 = a 35 \dfrac{84+a+y}{40+30+35}=\dfrac{a}{35} \implies 35 ( 84 + a + y ) = 105 a 35(84+a+y)=105a \implies 2940 + 35 y = 70 a 2940+35y=70a ( 1 ) \color{#D61F06}(1)

A F F B = A C F A A C F B = A O F A A O F B \dfrac{AF}{FB}=\dfrac{A_{CFA}}{A_{CFB}}=\dfrac{A_{OFA}}{A_{OFB}}

84 + y + 40 30 + 35 + a = 40 30 \dfrac{84+y+40}{30+35+a}=\dfrac{40}{30} \implies 30 ( 124 + y ) = 40 ( 65 + a ) 30(124+y)=40(65+a) \implies 1120 + 30 y = 40 a 1120+30y=40a ( 2 ) \color{#D61F06}(2)

Solve for a a in terms of y y in ( 2 ) \color{#D61F06}(2) then substitute in ( 1 ) \color{#D61F06}(1) , we have

a = 1120 + 30 y 40 a=\dfrac{1120+30y}{40}

2940 + 35 y = 70 ( 1120 + 30 y 40 ) = 1.75 ( 1120 + 30 y ) = 1960 + 52.5 y 2940+35y=70\left(\dfrac{1120+30y}{40}\right)=1.75(1120+30y)=1960+52.5y

2940 1960 = 52.5 y 35 y 2940-1960=52.5y-35y

980 = 17.5 y 980=17.5y

y = 56 \boxed{y=56}

0 pending reports

×

Problem Loading...

Note Loading...

Set Loading...