8 (?)
There are 6 triangles
There are 8 triangles inside a 10 sided decagon
There is 8 triangles in the Star of David.
8
There are 6 triangles in an 8 sided octagon
If it is in the form of two inverted triangles, then there are 8 triangles. If only the outline is used, there are 0 triangles.
A ten-sided geometric figure could have ten triangles drawn inside it, if you connect the vertexes. 8 triangles
Because all other polygons are made from triangles as for example an 8 sided octagon has 6 triangles within it or a 6 sided hexagon has 4 triangles within it.
Triangles are needed to form polygons of 3 sides or more as for instance a 6 sided hexagon needs 4 triangles and a 10 sided decagon needs 8 triangles.
tetrakaidecahedron
8 triangles will fit inside a 10 sided decagon
8 because there are 180 degrees in a triangle and 8*180 = 1440 degrees The interior angles of a 10 sided shape add up to 1440 degrees