Which of the equations are true identities? n(n-2)(n+2)=n^3-4n or (x+1)^2-2x+y^2=x^2+y^2+1

Where’s the

If two sides of a triangle are congruent, then the angles opposite those sides are congruent. the converse of the base angles theorem, states that if two angles of a triangle are congruent, then sides opposite those angles are congruent.