mk
bisector
X-axis and x-intercept start with x.
width
Angle Apothem AxesAxiom
I think vertex...
nonagon
One geometry word that starts with the letter "x" is "x-axis." In the Cartesian coordinate system, the x-axis is the horizontal line that represents the values of the independent variable. It is perpendicular to the y-axis, which represents the dependent variable values. The x-axis helps define the position of points in two-dimensional space.
A word that starts with X is a xylophone.
centagan: 100-gon
in geometry, width
The word you are looking for is:Trigonometry
How about a decagon which is a ten sided polygon