In order to determine the long of the chord, use the Pythagorean theorem to find the value of the long of the chord, as follow:
r² = l² + c²
where r = 13 in and c = 5 is the midpoit of the chord.
solve the previous equation for l and replace the other values r and c, as follow:
l² = r² - c²
l = √(r² - c²)
l = √(13² - 5²) in
l = √(144) in
l = 12 in
Hence, the length of the cord is 12 inches