Question

In Fig., there are five triangles. The measures of some of their angles have been indicated. State for each triangle whether it is acute, right or obtuse.

Answer 1

(i) This is a right triangle because one of its angles is 90$°$.
(ii) This is an obtuse triangle because one of its angles is 120$°$, which is greater than 90$°$.
(iii) This is an acute triangle because all its angles are acute angles (less than 90$°$).
(iv) This is a right triangle because one of its angles is 90$°$.
(v) This is an obtuse triangle because one of its angles is 110$°$, which is greater than 90$°$.