Given : Consider ΔABC to be a right angle triangle having sides a, b and hypotenuse c. Let BD be the altitude drawn on the hypotenuse AC.
To prove: ab = cx
Prove :
In ΔACB and ΔCDB
∠B = ∠B (Common)
(By AA similarity criteria)
⇒ ΔACB ∼ ΔCDB
(Corresponding Parts of Similar Triangles are propositional)
AB/ BD = AC/ BC
a/ x = c/ b
⇒ xc = ab
ab = cx
Hence, proved.