In a ΔBAC = 90° and AD is perpendicular to BC where D is a point on BC. If BD = 4 cm and CD = 5 cm, then the length of AD is equal to :

6 cm 4.5 cm $2\sqrt{5}$ cm $5\sqrt{2}$ cm

$2\sqrt{5}$ cm

In a ΔBAC = 90° BD = 4 cm CD = 5 cm The value of AD = \(\sqrt {BD × CD}\)   = \(\sqrt {4 × 5}\)  = $2\sqrt{5}$ cm