One angle of an isosceles obtuse triangle is 28°. Find measure of its obtuse angle in degree.
Show answer & explanation
Correct answer: D
Explanation
The correct answer is option 4 i.e. 123°.
Let the measure of the obtuse angle of the triangle be x°.
Given, triangle is an isosceles triangle then the angles other than obtuse angle will be equal to (57/2)° each.
Sum of all angles of a triangle = 180°
⇒ (57/2)° + 57/2)° + x° = 180°
⇒ x = 180° - 57°
⇒ x = 123°