In the given figure AD⊥BC and CD>BD. Show that AC>AB.
Given: AD ⊥ BC and CD > BD
To prove: AC > AB
Proof:
∠ADB=∠ADC=90°
AD⊥BC -----1
∠BAD<∠DAC
CD>BD -----2
In ∆ABD,
Using angle sum property of a triangle,
∠B=180°-∠ADB-∠BAD∠B=90°-∠BAD-----3
In ∆ADC,
Using angle sum property of a triangle,
∠ACD=90°-∠DAC ----- 4
From (2), (3) and (4), we get
∠B>∠C
Therefore, AC>AB.