How many lines of symmetry
for 4th grade

How many lines of symmetry does each shape have?

Lines of symmetry are imaginary lines that you can draw through a shape that divide the shape into two halves that are exact mirror images of each other. Different shapes have different numbers of lines of symmetry.

Square: A square has four sides of equal length and four right angles. It has four lines of symmetry - one vertical, one horizontal, and two diagonal lines. Each line of symmetry divides the square into two halves that are mirror images of each other.

Rectangle: A rectangle has two pairs of opposite sides of equal length and four right angles. It has two lines of symmetry - one vertical and one horizontal.

Triangle: The number of lines of symmetry a triangle has depends on the type of triangle it is. An equilateral triangle has three sides of equal length and three equal angles. It has three lines of symmetry - one vertical and two diagonal lines. An isosceles triangle has two sides of equal length and two equal angles. It has one line of symmetry - the line that goes through the midpoint of the base and bisects the opposite angle. A scalene triangle has no lines of symmetry.

Kite: A kite is a quadrilateral with two pairs of adjacent sides of equal length. It has one line of symmetry - the line that goes through the midpoint of the shorter diagonal and bisects the longer diagonal.

Pentagon: A regular pentagon has five sides of equal length and five equal angles. It has five lines of symmetry - one vertical, one horizontal, and three diagonal lines. Regular shapes with more sides like hexagon and octagon have the same number of lines of symmetry as they have sides. So a regular octagon has 8 and a regular nonagon has 9.

In this topic you are given diagrams of certain shapes and must decide how many lines of symmetry they have.