Respuesta :

equilateral triangle mean every sides and angles are equal 
so the measure of angles is 60 degrees 
 given that has an altitude of 15 m so this mean that 

sin 60 = altitude / hypotenuse 

sqrt3 /2 = 15/hyp.

hyp. = 15/(sqrt3 /2)

hyp. = 30/sqrt3 = 30sqrt3 / 3 = 10sqrt3

so in this way ve got that a side length is equal 10sqrt3 and the perimeter 

P = 3*10sqrt3 

P = 30sqrt3 m  so the 3rd choice is right,correct sure 

hope helped 


we know that

In the equilateral triangle every sides and angles are equal 

so

the measure of internal angles is equal to [tex] 60 [/tex] degrees 

see the attached picture to better understand the problem

In the right triangle ABC

[tex] sin 60=BC/AB [/tex]

where

BC is the altitude (opposite side angle [tex] 60 [/tex] degrees

AB is the hypotenuse

Clear AB

[tex] AB=BC/sin 60\\ AB=15/(\frac{\sqrt{3}}{2} )\\ AB=30/\sqrt{3}m [/tex]

Perimeter of the triangle is equal to

[tex] P=AB+BD+AD [/tex]

but remember that

[tex] AB=BD=AD [/tex]

so

[tex] P=3*AB\\ P=3*\frac{30}{\sqrt{3}} \\ \\ P=\frac{90}{\sqrt{3}} \\ \\ P=30\sqrt{3} m [/tex]

therefore

the answer is

[tex] 30\sqrt{3} m [/tex]


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