Solution:-
Consider the ∆ABC,
So, we have to prove that, AB × AE = AC × AD
Now, consider the ∆ADB and ∆AEC,
∠A = ∠A [common angle for both triangles]
∠ADB = ∠AEC [both angles are equal to 90o]
∆ADB ~ ∆AEC
So, AB/AC = AD/AE
By cross multiplication we get,
AB × AE = AC × AD