A circle is described by the equation x^2 + y^2 - 16x = 0. What is the length of the chord that is 4 units from the center of the circle?

$x^2 + y^2 - 16x = 0$

$(x^2 - 16x) + y^2 = 0$

$(x^2 - 16x + 64) + y^2 = 64$

$(x - 8)^2 + y^2 = 8^2$

$\text{Radius} = 8$
 

 

$a^2 + 4^2 = 8^2$

$a = 6.9282$
 

$\text{Length of chord} = 2a$

$\text{Length of chord} = 13.856 ~ \text{units}$