Question

in the square ABCD show that the two triangle a b c and ABC and congruent to each other

Answer 1

All sides are equal and AC is common
So by SSS congruency
∆abc congruent to∆adc

Answer 2

let BC is the diagonal in square ABCD
we have triangle ABC and triangle BCD :-
AB= CD ( sides of square are equal)
AD = BC ( same here)
BC = BC ( common)
hence , triangle ABC congruent to triangle BCD