Given: ABC is a right-angled triangle with ∠A as the right angle, and a perpendicular AD is drawn from the right angle vertex A to the hypotenuse BC. To prove: Triangles ∆DBA and ∆DAC are similar. Proof: In ∆DBA and ∆ABC, ∠BDA = ∠BAC = 90° And ∠ABD = ∠CBA Therefore, the remaining ∠BAD = ∠BCA So, ∆DBA and ∆ABC are equiangular Therefore, ∆DBA is similar to ∆ABC Again, in ∆DAC and ∆ABC, ∠ADC = ∠BAC = 90° ∠ACD = ∠BCA Therefore, the remaining ∠CAD = ∠CBA So, ∆DAC and ∆ABC are equiangular Therefore, ∆DAC is similar to ∆ABC Now, since ∆DBA is similar to ∆ABC and ∆DAC is similar to ∆ABC Therefore, ∆DBA is similar to ∆DAC (Proved)