An ellipse, sometimes referred to as an oval.
The name of a squashed circle is an oval
An ellipse
A diameter bisects a circle.
radius
A straight line from the center to the edge of a circle is called a radius. The radius measures the distance from the center to any point on the circumference of the circle.
A tangent. And it does not need to be a circle - it can be any curve.
It is a tangent
A Circle
radius
radius
The tangent.
Tangent.