Two circles of radii $a$ and $b\left(<a\right)$ touch each other internally. The distance between their centres is .

The maximum number of common tangents of two circles which intersect each other is _____.

The maximum number of common tangents of two circles which intersect each other internally is _____.

The number of tangents drawn to a circle at a point on the circumference of the circle is _____.

The number of tangents that can be drawn to a circle from a point inside the circle is _____.

Two perpendicular tangents are drawn to a circle from an external point. If the radius of the circle be $a$ unit, then the length of the tangent $=$ _____ unit.

When two circles touch each other, it is possible to draw a circle with two centres and the point of contact of two circles.

When two circles do not touch or do not intersect, the maximum number of common tangents that can be drawn to two circles is two.

Two circles do not intersect each other in more than two points.