Three Externally Tangent Circles With Same Size

Steps

1. Draw three lines i, g and h, each passing through the centre of one of the circles and the point of contact of the other two circles.
2. Denote the intersection of these three lines as S_1, and this point is the centre of the two circles sought.
3. Their radii are determined by the lengths of the segments S_1G and S_1F, where G and F are the intersections of the line i and the circle b(works with any circle and its intersecting line).