Answer:
5 cm
Step-by-step explanation:
Let the shorter side be a, longer side be b, hypotenuse be c
By Pythagorean theorem:
a² + b² = c²
a² + (a + 7)² = (a + 8)²
a² + a² + 14a + 49 = a² + 16a + 64
a² - 2a - 15 = 0
a² + 3a - 5a - 15 = 0
a(a + 3) - 5(a + 3) = 0
(a + 3)(a - 5) = 0
a = -3 or a = 5
Because a is a side length and is a positive number
a = 5
