Resposta :
[tex]\Large\boxed{\begin{array}{l}\sf d=\sqrt{(0-9)^2+(2-2)^2}\\\sf d=\sqrt{81}\\\sf d=9\end{array}}[/tex]

Explicação passo-a-passo:
.
A (2, 9) e B (2, 0)
A (2, 9)
xa=2
ya=9
B (2, 0)
xb=2
yb=0
[tex]d = \sqrt{(xa - xb) {}^{2} + (ya - yb) {}^{2} } [/tex]
[tex]d = \sqrt{(2 - 2) {}^{2} + (9 - 0) {}^{2} } [/tex]
[tex]d = \sqrt{(0) {}^{2} + (9) {}^{2} } [/tex]
[tex]d = \sqrt{0 + 81} [/tex]
[tex]d = \sqrt{81} [/tex]
[tex]d = 9[/tex]