Recordemos la ecuacion de distancia entre dos puntos :
<img src="https://tex.z-dn.net/?f=d%3D%20%5Csqrt%7B%28X2-X1%29%5E%7B2%7D%2B%28Y2-Y1%29%5E%7B2%7D%7D%20" />
a.
( - 2, 7) y (1, - 5) ; X2 = 1 ; X1 = - 2 ; Y1 = 7 ; Y2 = - 5
<img src="https://tex.z-dn.net/?f=d%3D%20%5Csqrt%7B%281-%28-2%29%29%5E%7B2%7D%2B%28-5-7%29%5E%7B2%7D%7D" />
<img src="https://tex.z-dn.net/?f=d%3D%20%5Csqrt%7B%283%29%5E%7B2%7D%2B%28-12%29%5E%7B2%7D%7D" />
d = \ sqrt{9 + 144}
<img src="https://tex.z-dn.net/?f=d%3D%20%5Csqrt%7B153%7D%3D12.3693" />
b) (8, - 9) y (1, 8) : X1 = 8 ; Y1 = - 9 ; X2 = 1 ; Y2 = 8
<img src="https://tex.z-dn.net/?f=d%3D%20%5Csqrt%7B%28X2-X1%29%5E%7B2%7D%2B%28Y2-Y1%29%5E%7B2%7D%7D" />
<img src="https://tex.z-dn.net/?f=d%3D%20%5Csqrt%7B%281-8%29%5E%7B2%7D%2B%288-%28-9%29%29%5E%7B2%7D%7D" />
<img src="https://tex.z-dn.net/?f=d%3D%20%5Csqrt%7B%28-7%29%5E%7B2%7D%2B%2817%29%5E%7B2%7D%7D" />
<img src="https://tex.z-dn.net/?f=d%3D%20%5Csqrt%7B49%2B289%7D" />
<img src="https://tex.z-dn.net/?f=d%3D%20%5Csqrt%7B338%7D%3D18.3847" />
c) W( - 3, 3) ; Q(20, y) : X1 = - 3 ; Y1 = 3 ; X2 = 20 ; Y2 = ?
<img src="https://tex.z-dn.net/?f=d%3D%20%5Csqrt%7B%28X2-X1%29%5E%7B2%7D%2B%28Y2-Y1%29%5E%7B2%7D%7D" />
[img = 10]
[img = 11]
Pero d = √577.
92
Elevamos en ambos lados al cuadrado
(√577.
92)² = [img = 12]
577.
92 = (23)² + (Y2 - 3)²
577.
92 = 529 + (Y2 - 3)²
577.
92 - 529 = (Y2 - 3)²
48.
92 = (Y2 - 3)²
48.
92 = (Y2)² - 6Y + 9
(Y2)² - 6Y - 39.
92 = 0 Donde a = 1 ; b = - 6 ; c = - 39.
92
[img = 13]
[img = 14]
[img = 15]
[img = 16]
[img = 17]
Y1 = [6 + 13.
98856] / 2 = 9.
994
Y2 = [6 - 13.
98856] / 2 = - 3.
99428
Y1 = 10
Y2 = - 4
En conclusion cualquiera de los dos valores 10 y - 4 Q(20 , 10) y Q(20, - 4), ambos puntos cumplen con la condicion de que la distancia sea √577.
92.