16Hit1600
Geometry and TrigonometryMediumFourth angle of a quadrilateral

Geometry and Trigonometry practice question

Three angles of a quadrilateral measure 90°, 110°, and 75°. What is the measure, in degrees, of the fourth angle?

Answer: 85

The angles of a quadrilateral sum to 360°: 360 − 275 = 85.

Common wrong answers

If you answered 95
95 is 180 − 85, treating the fourth angle as supplementary.
If you answered 275
275 is the sum of the three given angles.
If you answered -95
−95 subtracts the three angles from 180 instead of 360.

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