\(ABC\) is a triangle in which altitudes \(BE\) and \(CF\) to sides \(AC\) and \(AB\) are equal.
 
YCIND_241124_6816_18 (1).png
 
Show that
 
(i) \(∆ ABE ≅ ∆ ACF\)
 
(ii) \(AB = AC\), i.e., \(ABC\) is an isosceles triangle
 
Proof:
 
(i) In \(∆ABF\) and \(∆ACF\),
 
\(∠E=∠F\)  []
 
Therefore, \(∆AEB≅∆AFC\)  [By  Congruence rule]
 
Hence, we proved.
 
(ii)  \(AB=AC\) []
 
That is, \(ABC\) is an isosceles triangle.
 
Hence, we proved.