GeometryQuestion 410 of 550

An isosceles triangle has an apex angle of 40°. What is one base angle?

  1. 40°
  2. 80°
  3. 140°
  4. 70°
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Correct answer: 70°

The two base angles add up to 180 - 40 = 140°. Each angle is 140 ÷ 2 = 70°.

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Questions last reviewed: 21 October 2026