Answer:
Option C. 3√3
Step-by-step explanation:
Please see attached photo for brief explanation. 
In the attached photo, we obtained the following:
Opposite = a
Adjacent = 3
Hypothenus = 6
Angle θ = 60°
We can obtain the value of 'a' as follow:
Tan θ = Opposite /Adjacent
Tan 60° = a/3
Cross multiply 
a = 3 x Tan 60° 
But: Tan 60° = √3
a = 3 x Tan 60° 
a = 3 x √3
a = 3√3
Therefore, the length of the altitude of the equilateral triangle is 3√3. 
 
        
             
        
        
        
Answer: Example: 15 ÷ 5
Step-by-step explanation:
 
        
             
        
        
        
L = 24f
l/24 = f
Hope this helps!