Question 26
Prove that any real numbers $a$ and $b$ satisfy the inequality
$$
\sqrt{(a-3)^{2}+b^{2}}+\sqrt{a^{2}+(b-4)^{2}} \geqslant 5
$$
When does equality hold?
$$
\sqrt{(a-3)^{2}+b^{2}}+\sqrt{a^{2}+(b-4)^{2}} \geqslant 5
$$
When does equality hold?