Answer:
x = √30
Explanation:
For an equilateral triangle, the measure of the angle at each vertex is 60 degrees 
 
Thus, the angle 60 faces the side measure x 
 
Also, the given length is adjacent to the angle 60 measure 
 
Mathematically, the trigonometric ratio that links the adjacent and the opposite is the tan 
 
The tan is the ratio of the opposite to the adjacent 
 
Thus; 
 
Tan 60 = x/ root 10 
 
x = root 10 * tan 60 
 
x √(10 * √(3 
 
x = √30