Question

ABC IS a right angled triangle at B and D is a point on BC. If AD=18cm , BD=9cm and CD = 4 cm, find AC

Answer 1

$AB = \sqrt{ AD^{2} - BD^{2} } = \sqrt{243} = 9 \sqrt{3}$
$AC = \sqrt{ AB^{2} + BC^{2} } = \sqrt{412} = 2 \sqrt{103}$