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Sneha says: “A triangle can have an exterior angle of 70° with an interior opposite angle of 80°.” Why is she wrong?

Class 9Exterior Angle of a TriangleGeometry — Lines and Angles
  • AInterior angles cannot exceed 60°
  • BAn exterior angle is greater than each interior opposite angle
  • C70° and 80° must add to 180°
  • DExterior angles are always obtuse

Step-by-Step Solution

The exterior angle equals the sum of both interior opposite angles, so it must be greater than each of them. 70° cannot exceed 80°. (Exterior angles can be acute, so the second reason is false.)
Answer: B) An exterior angle is greater than each interior opposite angle

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