Which of the equations are true identities?
A. n(n − 2)(n + 2) = n^3 – 4n
B. (x+1)^2- 2x+y^2=x^2+y^2+1

To describe a sequence of transformations that maps triangle abc onto triangle a"b"c", a student starts with a reflection over the x-axis.how should the student complete the sequence of transformations to map triangle abc onto triangle a"b"c"? plz

Atriangle has a side lengths of 18cm, 80 cm and 81cm. classify it as acute obtuse or right?

In triangle △abc, ∠abc=90°, bh is an altitude. find the missing lengths. ah=4 and hc=1, find bh.