Fill up the blanks to make the following statements true:
(a) Sum of the angles of triangle is ___________.
(b) An exterior angle of a triangle is equal to the sum of ___________ opposite angles.
(c) An exterior angle of a triangle is always ___________ than either of the interior opposite angles.
(d) A triangle cannot have more than ___________ right angle.
(e) A triangle cannot have more than ___________ obtuse angle.
An exterior angle of a triangle is equal to the sum of the two interior opposite angles.