You can construct the following three types of tangent circles using the Construct Circle dialog box (Insert | Feature | Constructed | Circle):
Tangent
2 Lines - This option constructs a circle tangent to two lines.
The exact location is determined by the size of the circle and the
direction of the lines. Type a Diameter
value for the constructed after selecting the two input lines, and
then click Create. If the constructed circle
doesn't appear were expected, try changing the direction of one of
the lines.
Tangent
3 Lines - This option constructs a circle tangent to the three
input lines that form a triangle. Select the three input lines, and
then click Create.
Tangent 3 Circles - This option constructs a circle tangent to the three input circles. Select the three input circles, and then click Create. The tangent circle can either contain all three circles (circumscribed circle) or none of the three (inscribed circle).