Find the lengths of the sides of a triangle

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SUMMARY

The discussion focuses on calculating the lengths of the sides of a triangle given the altitudes of 14, 22, and 28. The solution involves applying the formula for the area of a triangle and the relationship between the sides and altitudes. The participants confirm the accuracy of the calculations, emphasizing the importance of understanding triangle properties in geometry.

PREREQUISITES
  • Understanding of triangle properties and the relationship between sides and altitudes
  • Familiarity with the area formula for triangles
  • Basic knowledge of geometry concepts
  • Ability to perform algebraic calculations
NEXT STEPS
  • Study the relationship between triangle altitudes and side lengths
  • Learn how to apply Heron's formula for area calculation
  • Explore the properties of different types of triangles (e.g., isosceles, equilateral)
  • Investigate advanced geometric concepts such as the Law of Sines and Cosines
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Students studying geometry, educators teaching triangle properties, and anyone interested in solving geometric problems involving altitudes and side lengths.

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Find the lengths of the sides of a triangle with 14, 22 and 28 as the lengths of its altitude.
 
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anemone said:
Find the lengths of the sides of a triangle with 14, 22 and 28 as the lengths of its altitude.

let the lengths opposite to altitudes of lengths 14,22,28 be x,y,z
then 2 times area
$14x = 22 y = 28 z$
or $x:: y:: z = \frac{1}{14}::\frac{1}{22}:: \frac{1}{28} = 44::28:: 22$(note all kept even to avoid fraction in computation )
so let x= 44t, y = 28t, z = 22t
area = $\dfrac{14x}{2}= 7x = 7 * 44 t = 308t$
using heros formula ( we get $s= \frac{44+28+22}{2}=47$)
$area = \sqrt{47*(47-44)*(47-28)*(47-22)}t^2 = \sqrt{47* 3 * 19* 25}t^2$
or $area = 5\sqrt{47*57}= 5\sqrt{2679}t^2$
so $308t = 5 \sqrt{2679}t^2$
or $t=\frac{308}{5\sqrt{2679}}$
so the sides are
$44t,28t,22t$ where t is as above
 
Last edited:
kaliprasad said:
let the lengths opposite to altitudes of lengths 14,22,28 be x,y,z
then 2 times area
$14x = 22 y = 28 z$
or $x:: y:: z = \frac{1}{14}::\frac{1}{22}:: \frac{1}{28} = 44::28:: 22$(note all kept even to avoid fraction in computation )
so let x= 44t, y = 28t, z = 22t
area = $\dfrac{14x}{2}= 7x = 7 * 44 t = 308t$
using heros formula ( we get $s= \frac{44+28+22}{2}=47$)
$area = \sqrt{47*(47-44)*(47-28)*(47-22)}t^2 = \sqrt{47* 3 * 19* 25}t^2$
or $area = 5\sqrt{47*57}= 5\sqrt{2679}t^2$
so $308t = 5 \sqrt{2679}t^2$
or $t=\frac{308}{5\sqrt{2679}}$
so the sides are
$44t,28t,22t$ where t is as above

Well done, kaliprasad!
 
a = 52.3657142876
b = 33.3236363648
c = 26.1828571438

From Wikipedia:
"Next, denoting the altitudes from sides a, b, and c respectively as ha, hb, and hc, and denoting the semi-sum of the reciprocals of the altitudes as H = (h_a^{-1} + h_b^{-1} + h_c^{-1})/2 we have[11]
A^{-1} = 4 \sqrt{H(H-h_a^{-1})(H-h_b^{-1})(H-h_c^{-1})}."
 
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