The original length of the tree is equal to the sum of the length of BC and AB.
In ∆𝐴𝐵𝐶
Hypotenuse = AB = ?
Base = AC = 12 m
Perpendicular = BC = 5 cm
Using Pythagoras theorem,
AB2 = BC2 + AC2
AB2 = 52 + 122
= 25 + 144
= 169
Hence, AB = √169
= 13 m
The original height of the tree = BC + AB
= 5 m + 13 m = 18 m
Therefore, the height of the tree is equal to 18 m.