Triangle sides

Geometry Level 3

Let a triangle with three sides a , b , c a, b, c , where a + b + c = 24 a+b+c=24 . Let X X be the biggest value among a + b , b + c a+b, b+c and a + c a+c .

What is the minimum possible value of X X ?


The answer is 16.

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

Pi Han Goh
Nov 6, 2015

Knowing that max ( x , y , z ) x + y + z 3 min ( max ( x , y , z ) ) min ( x + y + z ) 3 \max(x,y,z) \ge \dfrac{x+y+z}3 \Rightarrow \min( \max(x,y,z)) \ge \dfrac{\min(x+y+z)}3 . Let x = a + b , y = a + c , z = b + c x = a+b,y=a+c, z=b+c , we have

max ( a + b , a + c , b + c ) ( a + b ) + ( b + c ) + ( c + a ) 3 = 24 × 2 3 = 16 \max(a+b,a+c,b+c) \ge \dfrac{(a+b)+(b+c)+(c+a)}3 = \dfrac{24\times2}3 = 16

Hence the minimum value of the maximum values of the numbers a + b , a + c , b + c a+b,a+c,b+c is 16 \boxed{16} and it can be achieved when a + b = a + c = b + c a+b=a+c=b+c or a = b = c = 8 a=b=c=8 .

0 pending reports

×

Problem Loading...

Note Loading...

Set Loading...