Question

Three angles of a quadrilateral 98, 72 and 105 degree. What is the exterior angle of the fourth angle?

Answer 1

The sum of the three angles is 98° + 72° + 105° = 275°. 

The fourth angle of the quadrilateral = 360° - 275° = 85°. 

The exterior angle of the fourth angle is 180° - 85° = 95°

Answer 2

We know, by angle sum property, the sum of angles of a quadrilateral is 360°.

The given angles are 98°, 72°, 105°.

Let the fourth angle be x°.

Then, 98° + 72° + 105° + x = 360°

⇒ 275° + x = 360°

⇒ x° = 360° - 275°

Therefore, the fourth angle is x = 85°

The exterior angle of the fourth angle is 180° - 85° = 95°