Applying the Pythagoras Theorem, the length of RS = 8 units.
According to the figure,
Diameter = 16 +4 = 20 units
So, the Radius = Diameter/2 = 20/2 = 10 units
Now,
Let the center be M, then
MT = 10 - 4 = 6 units
RT = x units
The radius is perpendicular to the chord,
So, MTR will be a right-angled triangle,
We will apply the Pythagoras theorem,
So, we have :

Here, RT = x units
TM = 6 units and RM = radius = 10 units
Putting these values in the Pythagoras theorem,

Thus, the length of RS = 8 units.
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