Abstract: The, present paper deals with the analytical determination of the axis and the angle of rotation for a retractable landing gear. To facilitate the use of computer, the socalled rotation matrix [A] about a skew axis PP is worth applying. If the coordinates of three points, say A, Band C,of a rigid body before and after rotation about an axis through point P are known, the rotation matrix [A] can be easily calculated as follows: where subscripts 1 and 2 stand for points before and after rotation respectively. Here a simple technique for obtaining the third point C from the two given points A and B of a rigid body is introduced. Any arbitrary point on the line passing through P and perpendicular to the plane formed by two given straight lines PA and PB can be taken as the point C.In addition, some improvement in calculating the axis and the angle of rotation has been made. A numerical example of landing gear problem is included at the end of the paper.The results obtained may be applied to design of retrac-table mechanisms for antennas and sensors on spacecraft as well.