# If △ABC is an isosceles triangles with ∠C = 90° and AC = 5 cm, then AB is:

If △ABC is an isosceles triangles with ∠C = = 90° and AC = 5 cm, then AB is:
[A]$5\sqrt{2}cm$
[B]$2.5 cm$
[C]$5 cm$
[D]$10 cm$

$\mathbf{5\sqrt{2}}cm$

AC = BC = 5 cm
∴ AB $=\sqrt{AC^{2}+BC^{2}}$
$= \sqrt{5^{2}+5^{2}} = \sqrt{50} = 5\sqrt{2} cm$
Hence option [A] is the right answer.