The diameter of the reservoir is determined as 80 meters.
How to calculate the diameter of the reservoir?
The diameter of the reservoir is calculated by applying intersecting chord theorem as follows;
let the diameter of the reservoir = D
Applying intersecting chord theorem, we will have;
AB² = AC × (length AC + diameter of the reservoir)
(42²) = 18 × (18 + D)
We will simplify the equation above and calculate the value of D as;
1764 = 324 + 18D
18D = 1,440
D = 1,440 / 18
D = 80 m
Thus, the diameter of the reservoir is 80 m.