line that touches circle at one point
tangent
line that passes through the midpoint
bisector
line that crosses at 90 degrees
perpendicular
an angle formed by 2 radii of a circle
centralangle
a line segment with both endpoints on a circle
chord
an angle formed by 2 chords that share a common endpoint
inscribedangle
a portion of the circumference
arc
a line that touches a circle at exactly one point
tangent
distance across a circle that passes through the centre
diameter
line segment from the centre of a circle to any point on the circle
radius
if 2 angles add up to 180 they are...
supplementary
distance around a circle
circumference