To solve this problem you must apply the proccedure shown below:
 1. You have the following information given in the problem above: The<span> regular octahedron with edges that are 2.1 inches.
 2. Therefore, you must apply the formula for calculate the volume of a octahedron, which is:
 V=(a^3</span>√2)/3
 3. Therefore, you have:
 V=((2.1 inches)^3√2)/3
 V=178.30 inches^3
        
             
        
        
        
Answer:

Step-by-step explanation:
i = -1 
 This is a complex number
in here we take -1 = i 
 
        
             
        
        
        
The question marked angle is equal to 138