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Three congruent isosceles triangles DAO, AOB and OBC have AD=AO=OB=BC=10 and AB=DO=OC=12. These triangles are arranged to form trapezoid ABCD, as shown. Point P is on side AB so that OP is perpendicular to AB.

 

 

Point $X$ is the midpoint of AD and point Y is the midpoint of BC. When X and Y are joined, the trapezoid is divided into two smaller trapezoids. The ratio of the area of trapezoid ABYX to the area of trapezoid XYCD in simplified form is p:q. Find p+q.

 

 Mar 15, 2020
 #3
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I am not putting in every step.  If you have any questions you can ask.

 

area O'AB : area O'XY : area O'DC

    10^2      :       15^2     :       20^2

      100      :         225     :        400

        1       :         2.25   :         4

 

let OO'=2h

 

Area of  O'AB = 0.5*12h= 6h

it follows that

area of  O'XY = 2.25*6h = 13.5h    and then that   area of AXYB = 13.5h-6h = 7.5h

it also follows that

area of O'DC = 4*6h = 24h   and then that           area of  XDCY = 24h-13.5h = 10.5h

 

so

area of AXYB : area of AXYB

       7.5           :     10.5

         5            :        7

 

Anyone who is interested can finish it from there   laugh

 Jun 11, 2020

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