Geometry Problem

Geometry Level 3

$\Delta\text{ABC}$ is an isosceles triangle and $x$ is the size of $\angle DEA$ . Find the value of $x$ in degrees.

The answer is 20.

1 solution

Finn Hulse
Mar 27, 2014

Let $F$ be a point such that $EF$ is parallel to $BC$ . Let $G$ be the intersection of $CD$ and $BE$ . It is obvious that $FEG$ is similar to $BCF$ . Thus angle $x$ is $90-70$ degrees, or $\boxed{20}$ .

hey @Finn Hulse ,can u explain some more

Rishabh Jain - 7 years, 2 months ago

What I'm saying is that you have to draw a point $F$ to the left of the triangle and then everything just fits into place. :D

Finn Hulse - 7 years, 2 months ago

Geometry Problem

The answer is 20.

1 solution

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