The measure of one of the exterior angles of a triangle is twice one of the interior opposite angles and the measure of the other interior opposite angles is 60° . The triangle is a/an:
Answer & explanation
Correct answer: option 4
Let one of the interior opposites angles = a
The measure of one of the exterior angle = a + 60°
According to the question,
⇒ 2 × one of the interior opposite angles = a + 60°
⇒ 2a = a + 60°
⇒ 2a - a = 60°
⇒ a = 60°
Now the third interior angle = 180° - a - 60° = 180° - 60° - 60° = 60°
Now, if all the angles are same and of 60o then we can say that it is a equilateral triangle.