Sign Up
Login
Sign in
Sign in
←
Exercise 382
→
« Prev
Next »
Search
Go to
{{searchResults.length}} result
s
for “{{searchWords}}”
No results found for “{{searchWords}}”
× back to contents
§{{x[0]}}
{{x[1]}}
Table of Contents
Browse by chapter, year or number
Similar Triangles
areas
pythagoreanTheorem
circles
quadrilaterals
threeDimensionalGeometry
trigonometry
conic
miscellaneous
exercises solutions
Exercise 382
In $\triangle BAC$, $\angle BAC=30^\circ$, $AB=12$, $AC=8$. Points $D,E$ lie on $\overline{AB},\overline{AC}$ respectively. What is the minimum possible value of $BE+DE+CD$?
← Back to Problem 382
Solution
Reflect $B$ in $AC$ to $B'$ and $C$ in $AB$ to $C'$. Then $BE+DE+CD=B'E+ED+DC'\ge B'C'$.
$AB'=12$, $AC'=8$, $\angle B'AC'=3\cdot30^\circ=90^\circ$, so $B'C'^2=12^2+8^2=208$.
$B'C'$ meets $AC$, $AB$ at points $E,D$ on the sides, so equality holds.
The minimum is $\sqrt{208}=\boxed{4\sqrt{13}}$.
Search
Go to
Prev
Next
×
Contact Us
Send
Thanks! Your message has been sent.