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In $\triangle ABC$, shown here, $\overline{AB}$ and $\overline{AC}$ have each been divided into four congruent segments. What fraction of triangle $ABC$ is shaded? Express your answer as a common fraction.


 Oct 15, 2019

Let the area  of  triangle ABC  =  A


Discounting the bottom unshaded area the remaining triangle  is  (3/4)^2 * area of ABC  =


(9/16) A       


So....the area  of the bottom unshaded area  = A  - (9/16)A  =  (7/16)A      (1)


Looking at  the "top" triangle  composed of   the top shaded area and the underneath unshaded area......the area of this triangle   =  (1/2)^2 * area of ABC  =  (1/4)A


And the area of the top shaded area  =  (1/4)^2 * area of ABC  =  (1/16)A


So....the   area  of the second unshaded region  =   (1/4)A - (1/16)A  =  (3/16)A    (2)


So.....the area of the shaded regions  =


area of ABC   - the areas of the two unshaded regions  = 


area of ABC  -  (1) - (2)  =


A   -   (7/16)A  -  (3/16)A  =


(6/16)A  =  (3/8) A


So....the shaded areas  are (3/8)  the area of  triangle ABC



cool cool cool

 Oct 15, 2019

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