GeometryQuestion 427 of 550

A quadrilateral has three angles of 90°, 100° and 80°. What is the fourth angle?

  1. 90°
  2. 80°
  3. 100°
  4. 110°
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Correct answer: 90°

The angles of a quadrilateral add up to 360°. 360 - 270 = 90°.

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Questions last reviewed: 21 October 2026