Answer:
The length side of the triangle is [tex]\frac{10\sqrt{3}}{3}\ cm[/tex]
Step-by-step explanation:
we know that
The equilateral triangle has three equal sides and three equal internal angles of measure of 60 degrees each.
Let
b------> the length side of the equilateral triangle
Applying Pythagoras theorem
[tex]b^{2}=(b/2)^{2}+5^{2}\\\\ b^{2}-(b/2)^{2}=25\\\\ (3/4)b^{2}=25\\ \\b^{2} =25*4/3\\ \\b=\frac{10}{\sqrt{3}}\ cm\\ \\b=\frac{10\sqrt{3}}{3}\ cm[/tex]