Am i going blank?

Geometry Level 3

The medians of a triangle are 5 cm, 6cm and 7cm. The area of this triangle can be expressed as a b a\sqrt{b} where a a and b b are positive integers. Find a + b a+b .


The answer is 14.

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.

4 solutions

Jack D'Aurizio
Jun 28, 2014

The medians of a triangle satisfy the triangular inequality. Moreover, if Δ M \Delta_M is the area of the triangle having the medians as sides and Δ T \Delta_T is the area of the original triangle, Δ T = 4 3 Δ M \Delta_T=\frac{4}{3}\Delta_M holds, so it is sufficient to find Δ M = 6 6 \Delta_M=6\sqrt{6} through Heron's formula in order to have Δ T = 8 6 \Delta_T=8\sqrt{6} .

Exactly, nice solution i did it same way.

Mardokay Mosazghi - 6 years, 11 months ago

The area if the triangle = 3 * area of triangle formed out of 2/3 the median.
Area of this 2/3 midian:-
sides = 2/3(5,6,7 ). Area =(2/3)^2 * area of (5,6,7)
s=(5+6+7)/2 = 9......... s - a = 4,.......s - b = 3,..........s - c = 2
So required area = 3 * (4/9) * sqrt{9 * 4 * 3 * 2}
=8 * sqrt(6)...........= .a * sqrt(b)....>>>> a +b = 14



Sayed Nesta
Jun 29, 2014

a=5 , b=6 , c=7

area = 1/2 x a x b = ...........1/2 x 5 x 6 = 15

15 = 5 x -/`9``` = 5+9 = 14 ......... ^_^

Can you please explain your steps ?

Niranjan Khanderia - 6 years, 11 months ago

ايش هذا يا رجل ؟؟؟ انتا استخدمت قانون ايه ؟

Ahmed Yahya - 6 years, 10 months ago
Himanshu Arora
Jun 28, 2014

Refer this

I used appollonius theorem related to medians and got a^2 = 74 , b^2 = 61, c^2 = 85.. ( 3 equations, 3 unknowns).. After some tedious algebra, i somehow seem to get an answer of sqrt(972.25) which does not seem right. The link between the median triangle and the original triangle is neat and elegant and the necessity is reinforced because of the square roots

Sundar R - 6 years, 11 months ago

0 pending reports

×

Problem Loading...

Note Loading...

Set Loading...