2007-09-12 15:32:15 · 15 answers · asked by Anonymous in Science & Mathematics ➔ Mathematics
39/3 = 13
2007-09-12 15:35:30 · answer #1 · answered by Runa 7 · 1⤊ 1⤋
triangle = 3 sides
equilateral = all sides same length.
Therefore, each side = 39/3 = 13 inches.
Law of sines: each angle is proportional to the side facing it. SInce all sides are equal, then all angles must be equal.
In any (plane) triangle, the sum of the three angles is always 180 degrees.
Therefore all angles are 60 degrees each.
place the triangle so that it rests on one side. Draw a perpendicular from the top angle to the middle of the bottom side. It must divide the top angle in two (each smaller triangle has a 60 degree angle on the outer bottom and a 90 degree angle at the perpendicular, therefore the top angles must be 30 for each one.
The bigger triangle is therefore divided in exactly two identical triangle (except for the orientation). This means the base is divided in 2 (2 halves, each 13/2 inches long)
The height is one side of a small right angle triangle, where the hypotenuse is 13 inches and the base is 13/2.
By Pythagorean theorem, the square of the height is the difference of the other two squared sides:
h^2 = (13)^2 - (13/2)^2 = (507/4)
h = √507 / √4 = (√507 / 2) inches
Area = (1/2) * base * height
Area = (1/2) * (13/2) * (√507 / 2) = 13*√507 / 8
Area = approx. 36.59 in^2
2007-09-12 15:54:43 · answer #2 · answered by Raymond 7 · 1⤊ 1⤋
An equilateral triangle is a triangle with 3 equal sides. So just divide 39 by 3 we get 13 inches per side.
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2007-09-12 15:42:27 · answer #3 · answered by revilo_siah 1 · 1⤊ 0⤋
equilateral triangles have 3 equal sides, and all 3 connect at the same angle. so if the triangle has a perimeter of 39 inches then each side is 1/3 of that. so each side is 13 inches.
2007-09-12 15:37:15 · answer #4 · answered by cronotknight 2 · 1⤊ 0⤋
An equilateral triangle has equal sides.
equi = equal
lateral = sided
If a triangle has three sides and they all add up to that perimeter of 39, then you can divide 39 into three pieces.
Each side is 13 inches long.
Also, every equilateral triangle has three 60 degree angles.
2007-09-12 15:37:49 · answer #5 · answered by Anonymous · 1⤊ 0⤋
An equilateral triangle has 3 equivalent facets, so those will all be 13 inches in length. you additionally can think of of an equilateral triangle as 2 perfect angled triangle back-to-back, the hypotenuse being 13 inches, the shortest area 13/2 = 6.5. you may then use pythagoras to confirm the 0.33 area of the properly suited-angled triangle...it somewhat is likewise the vertical height of the unique equilateral triangle. desire it fairly is smart!
2016-12-26 08:19:57 · answer #6 · answered by ? 3 · 0⤊ 0⤋
Well if its equilateral you know all 3 sides are the same length and that all 3 angles are equal as well.
So divide the permiter by 3 to get 13 and each angle is 60.
2007-09-12 15:37:59 · answer #7 · answered by Anonymous · 1⤊ 0⤋
So you've got a equilateral triangle with
13" sides. Can't you work out the rest?
Hint: Drop a vertical from the vertex,
and you've got two 30, 60, 90 triangles
with 13" hypotenuses.
2007-09-12 15:38:23 · answer #8 · answered by Irv S 7 · 1⤊ 1⤋
Equilateral means equal sides. So each side would have to be 13 inches.
2007-09-12 15:42:37 · answer #9 · answered by phrog_1975 3 · 2⤊ 0⤋
"Equilateral" means "sides of equal length". If a triangle has three equal length sides, and the sum of those lengths adds up to 39, then each side is.....
2007-09-12 15:36:00 · answer #10 · answered by Boots McGraw 5 · 2⤊ 0⤋