Question

which shape has exactly 1 line of symmetry?

Explanation:

Step1: Analyze the first shape (triangle)

The first triangle appears to be a scalene triangle (all sides unequal), which has 0 lines of symmetry. If it were isoceles, it would have 1, but from the diagram, it looks scalene. So not this one.

Step2: Analyze the second shape (star)

A regular star (like a hexagram) has multiple lines of symmetry (6, for a regular hexagram), so it has more than 1.

Step3: Analyze the third shape (arrow - like triangle)

This shape (a triangle with a notch or an arrow - head - like triangle) has exactly 1 line of symmetry. If we draw a vertical line through the tip of the arrow and the base, it divides the shape into two mirror - image halves.

Step4: Analyze the fourth shape (rhombus)

A rhombus has 2 lines of symmetry (the diagonals), so it has more than 1.

Answer:

The third shape (the arrow - like triangle) has exactly 1 line of symmetry.