AD is an altitude of an isosceles triangle ABC in which AB = AC. Show that
(i) AD bisects BC
(ii) AD bisects ∠A.
Given: AD is an altitude of an isosceles triangle ABC in which AB = AC.
To Prove: (i) AD bisects BC
(ii) AD bisects ∠A.
Proof: (i) In right ∆ADB and right ∆ADC,
Hyp. AB = Hyp. AC | Given
Side AD = Side AD | Common
∴ ∆ADB ≅ ∆ADC | RHS Rule
∴ BD = CD | C.P.C.T.
⇒ AD bisects BC.
(ii) ∵ ∆ADB ≅ ∆ADC
| Proved in (i) above
∴ ∠BAD = ∠CAD | C.P.C.T.
⇒ AD bisects ∠A.