which type of triangle will always have at least 1-fold reflectional symmetry? right triangle obtuse triangle acute triangle isosceles triangle

An isosceles triangle will always have at least 1-fold reflectional symmetry.

Key idea

• A figure has reflectional symmetry if it can be folded along a line so that both halves match exactly.

• An isosceles triangle has two equal sides, so there is always a line through its vertex between the equal sides that splits it into two mirror-image halves.

Why the other options fail

• Right triangle: Only some right triangles are isosceles; a general right triangle with three different side lengths has no line of symmetry.

• Obtuse triangle: If all three sides are different (scalene obtuse), it has no reflectional symmetry.

• Acute triangle: A scalene acute triangle has no line of symmetry; only an isosceles acute one does.

Final answer

So, among the options

right triangle, obtuse triangle, acute triangle, isosceles triangle

the type that will always have at least 1-fold reflectional symmetry is: Isosceles triangle.

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