In the world of Drafting and Architecture, it is called a Scale.
A triangle ruler is called a 'set square. '
These are triangular-shaped and sometimes have a cut-out center on it
this ruler can be used for measuring and the term for this object is "scale"
a right triangle
a right triangle
A triangle with three equal angles is an equilateral triangle.
That number is called the "perimeter" of the triangle.
An equilateral triangle can also be called a "regular" triangle
first line indent marker
Hanging indent is the term for the bottom triangle at the 0 mark on a horizontal ruler.
with a ruler
Use a ruler.
you use a ruler
three size
its the pointy bit
Use a ruler.
Measure it with a ruler.
You use a ruler or tape measure.
You can measure it with a ruler.
you get a ruler and see if it is a equaliteral triangle, icosles,or scalene witch it is equaliteral