X = Cateto Menor
Y = Cateto Mayor
Z = Hipotenusa
Pero
Y = 7 + X
Z = Y + 1 ; Remplazo el valor de Y
Z = (7 + X) + 1 = 8 + X
Aplico Pitagoras
Cat² + Cat² = H²
(X)² + (7 + X)² = (8 + X)²
X² + 49 + 14X + X² = 64 + 16X + X²
2X² + 14X + 49 = 64 + 16X + X²
2X² - X² + 14X - 16X + 49 - 64 = 0
X² - 2X - 15 = 0 : Donde a = 1 ; b = - 2 ; c = - 15
<img src="https://tex.z-dn.net/?f=X%3D%5Cfrac%7B-b%5Cpm%20%5Csqrt%7Bb%5E2-4ac%7D%7D%7B2a%7D" />
<img src="https://tex.z-dn.net/?f=X%3D%5Cfrac%7B-%28-2%29%5Cpm%20%5Csqrt%7B%28-2%29%5E2-4%281%29%28-15%29%7D%7D%7B2%281%29%7D" />
<img src="https://tex.z-dn.net/?f=X%3D%5Cfrac%7B2%5Cpm%20%5Csqrt%7B4%2B60%7D%7D%7B2%7D" />
<img src="https://tex.z-dn.net/?f=X%3D%5Cfrac%7B2%5Cpm%20%5Csqrt%7B64%7D%7D%7B2%7D" />
<img src="https://tex.z-dn.net/?f=X%3D%5Cfrac%7B2%5Cpm%20%5C%208%7D%7B2%7D" />
X1 = [2 + 8] / 2 = 5
X2 = [2 - 8] / 2 = - 3
Tomo X1 = 5.
Osea X = 5 m
Cateto menor = 5 m
Cateto Mayor = 5 + 7 = 12 m
Hipotenusa = 5 + 8 = 13 m
Prueba
13² = 12² + 5²
169 = 144 + 25
169 = 169.