The square root of 400 is 20
        
                    
             
        
        
        
Answer:
length of chord is 6cm
Step-by-step explanation:
Here, we are to calculate the length of the chord.
It should be understood that the chord has a length of 0.8cm from the center of the circle of radius 3cm, thereby forming two right-angled triangles with the radius 3cm being the hypotenuse of each and 0.8cm being the height of each.
Now, the chord is divided into 2 by this height dropping from the center of the circle. To calculate the first half, we use Pythagoras’ theorem with 3cm being hypotenuse and 0.8cm being the other side. 
mathematically;
3^2 = 0.8^2 + l^2
9 = 0.64 + l^2
l^2 = 9-0.64
l^2 = 8.36
l = √(8.36)
l = 2.89 approximately 
The length of the chord would be 2l = 2 * 2.89 = 5.78 cm which is 6cm to the nearest length 
 
        
             
        
        
        
Answer:
x > 0, if not 4/x < 0
0 < 4/x < 6/7
0 < 28/x < 6
0 < 28 < 6x
0 < 4 2/3 < x
Step-by-step explanation: