The Total solution for NCERT class 6-12
Given, D is a point on the side BC of atriangle ABC such that ∠ADC = ∠BAC.
In ΔADC and ΔBAC,∠ADC = ∠BAC (Already given)∠ACD = ∠BCA (Common angles)∴ ΔADC ~ ΔBAC (AA similarity criterion)We know that corresponding sides of similar triangles are in proportion.
∴ CA/CB = CD/CA
⇒ CA2 = CB.CD.
Hence, proved.