4
7
Yes
The equator is the only parallel that is a great circle because it is centered on the Earth's axis of rotation. This means that it divides the Earth into two equal hemispheres and its circumference is the maximum possible for a circle on the Earth's surface. Other parallels are smaller circles and not great circles.
A circle is one possible answer.
No two circles can intersect more than twice. Each circle can intersect with each other circle. Thus there ought to be 2 × 30 × (30 - 1) intersections. However, this counts each intersection twice: once for each circle. Thus the answer is half this, giving: maximum_number_of_intersections = ½ × 2 × 30 × (30 - 1) = 30 × 29 = 870.
6 maximum points of intersection
There are infinitely many possible answers. A circle is one.
Infinite when chords are parallel to the circle's diameter
A circle does not have a set of parallel lines in the traditional sense, as parallel lines are defined as lines that never intersect and remain equidistant from each other. However, you can draw lines that are tangent to a circle at various points, and these tangent lines can be parallel if they are at the same distance from the center of the circle. But in the context of the circle itself, it does not contain parallel lines.
a circle
No, parallel lines are straight lines.
the shape that has parallel face is circle