Explanation:
Hello!!!
Let's workout with this figure.
BC is a chord, O is the centre and OA is the perpendicular bisector.
AB = 1/2 of BC (according to circle's theorem)
so, A B = 1/2 × 25.6
Therefore, the measure of AB is 12.8.
now, let's have a small work with triangle AOB.
as it is a Right angled triangle, taking angle B as refrence angle we get,
p=x
b=12.8
h= OB = 16 (it is also a radius.)
now,
by Pythagoras relation we get,

or, x = root 16^2- 12.8 ^2
by simplification, we get;
the measure of x is 9.6.
Therefore, the value of x is 9.6.
Hope it helps...