Define a triangle.

Which of the following statements are true (T) and which are false (F).

(i) Sum of the three angles of a triangle is 180°.

(ii) A triangle can have two right angles.

(iii) All the angles of a triangle can be less than 60°.

(iv) All the angles of a triangle can be greater than 60°.

(v) All the angles of a triangle can be equal to 60°.

(vi) A triangle can have two obtuse angles.

(vii) A triangle can have at most one obtuse angles.

(viii) If one angle of a triangle is obtuse, then it cannot be a right angled triangle.

(ix) An exterior angle of a triangle is led than either of its interior opposite angles.

(x) An exterior angle of a triangle is equal to the sum of the two interior opposite angles.

(xi) An exterior angle of a triangle is greater than the opposite interior angles.

Fill in the blanks to make the following statements true :

(i) Sum of the angles of a triangle is ……

(ii) An exterior angle of a triangle is equal to the two …… opposite angles.

(iii) An exterior angle of a triangle is always …..than either of the interior opposite angles.

(iv) A triangle cannot have more than ….right angles.

(v) A triangles cannot have more than ….. obtuse angles.

Write the sum of the angles of an obtuse triangle.

In Δ ABC, if ∠B = 60°, ∠C = 80° and the bisectors of angles ∠ABC and ∠ACB meet at a point O, then find the measure of ∠BOC.