Answer:
√ 41 (or 6.40 in decimal form)
Explanation:
By Pythagorean theorem,
for a right triangle with sides a and b and hypotenuse h, the following formula is true:
a² + b² = h²
or
h = √ (a² + b²).
in this case, it is given that a and b are 4 and 5 units respectively
hence
h = √ (4² + 5²) = √ (16 + 25) = √ 41 = 6.40