Find the line of symmetry of a triangle
Today we'll learn about line symmetry. A shape has line symmetry if we can fold it so both halves match exactly.
Look at this triangle. Could we fold it so the two sides line up?
Where would we fold? Try to picture a fold line straight down the middle.
Right here! We draw a line straight down from the top point to the bottom edge.
The left side mirrors the right side. Every point on the left has a matching point on the right.
That fold line is called a line of symmetry. This triangle has exactly one.
But not every shape works. This lopsided triangle has no fold that makes matching halves — it has zero lines of symmetry.
Some shapes have more than one. A rectangle has two lines of symmetry — one vertical and one horizontal.
A line of symmetry splits a figure into two matching halves. To find them, look for every fold that makes the two sides line up perfectly.
Now you try. Count the lines of symmetry. How many symmetry lines?