Answer:
a = 1.5
Explanation:
Assuming side 'a' is the short side of a right triangle with the given dimensions, we can find it using the Pythagorean theorem.
c² = a² +b²
a = √(c² -b²) = √(2.5² -2²) = √2.25
a = 1.5
_____
The ratio of the given sides is 2.5 : 2 = 5 : 4. Only one right triangle has hypotenuse and long side in the ratio 5 : 4. That is the 3-4-5 triangle. This means the short side is 3/5 of the hypotenuse, or (3/5)(2.5) = 1.5
The length of side 'a' is 1.5 units.