I think its b because of its relation to the base
        
                    
             
        
        
        
Answer:
It says it right there. 
the answer that you need is 300
Step-by-step explanation:
Brainiest
 
        
                    
             
        
        
        
72 ÷ o should be the algebraic expression.
 
        
             
        
        
        
In this case we are dealing with the pythagorean theorm involving right angled triangles. This theorm states that a^2 + b^2 = c^2 which means the square of the hypotenuse (side c, opposite the right angle) is equal to the square of the remaining two sides.
In this case we will say that a = 3963 miles which is the radius of the earth. c is equal to the radius of the earth plus the additional altitude of the space station which is 250 miles; therefore, c = 4213 miles. We must now solve for the value b which is equal to how far an astronaut can see to the horizon.
(3963)^2 + b^2 = (4213)^2
b^2 = 2,044,000
b = 1430 miles.
The astronaut can see 1430 miles to the horizon.