Answer: 21.44 cm
Step-by-step explanation:
Given
Radius r=15 cm
distance of chord from the center is 10 cm
From the figure, the length of the chord is AC
Applying Pythagoras

The length of the chord is 
Step-by-step explanation:
y=mx+c
Take c from both sides:
y-c = mx
Divide both sides by m:
(y-c) / m =x
Now swap sides to make it prettier:
x = (y-c) / m
The answer is 113. As said by the calculator
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For the solution I isolated the variable by dividing each side by factors that don't contain the variable.
x = -6 + ∛2 / 2
x ≈ -5.37003947
Hope this helps!! :3
(If not, sorry)