Final value of a if distance between the points (-9 cm, a cm) and (3 cm, 3cm) is `13` cm.

The distance between the centres of two circles having radii 8 cm and 3 cm, is 13 cm. The length (in cm) of the direct common tangent of the two circle is

The distance between the centres of two circles having radii 9 cm and 4 cm is 13 cm. What is the length of the direct common tangent of these circles ?

The distance between the centres of two circles of radii 3.4 cm and 1.8 cm is 3.7 cm. Then the circles are :

The parallel sides of a trapezium measure 14 cm and 18 cm and the distance between them is 9 cm. The area of the trapezium is

Radii of two circles are 2 cm and 3 cm and the distance between the centres of them is 13cm . Find the length of their oblique common tangent.

The diameters of two circles are 18 cm and 8 cm. The distance between their centres is 13 cm. What is the number of common tangents?