The social groups that he mentions are Hindus and Muslims. Yes, these groups were easily identifiable by their dressing, tradition, culture, etc. For instance, Kalam used to wear a cap on his head which identified him as a Muslim. Ramanadha Sastry wore a sacred thread.
ABC is a triangle in which altitudes BE and CF to sides AC and AB are equal (see Fig). Show that
(i) ∆ ABE ≅ ∆ ACF
(ii) AB = AC, i.e., ABC is an isosceles triangle.

∆ABC is an isosceles triangle in which AB = AC. Side BA is produced to D such that AD = AB (see Fig. 7.34). Show that ∠ BCD is a right angle.

