Based on the right-angled triangle ABC, the length of z is equal to: C) 25 cm.
In Mathematics and Geometry, Pythagorean theorem is an Euclidean postulate that can be modeled or represented by the following mathematical equation:

Where:
- a is the opposite side of a right-angled triangle.
- b is the adjacent side of a right-angled triangle.
- c is the hypotenuse of a right-angled triangle.
In order to determine the length of z, we would have to apply Pythagorean's theorem as follows;

z = 25 cm.
Complete Question:
If x=15 cm and y=20 cm, what is the length of z?
A) 23 cm B) 26cm C)25cm D)27 cm