Trikonasana (Sanskrit: त्रिकोणासन) is a standing posture in which the body forms a shape of two triangles (hence the name).
Stand with you legs apart, the feet on a distance of 4 feet from one another. The back foot is rotated in a 5 degrees angle forward while the front foot is aligned with the axis of the mat. both knees are straight.
As you lean down into the pose try to bring your pelvis perpendicular to the floor. Extend the upper arm up to the ceiling and push with the lower hand against your foot and extend your spine. focus your gaze on the thumb of the lifted hand.
In some schools trikonasana is called uthita trikonasana (meaning extended triangle pose). This emphasizes the importance of lengthening and extending the torso rather than reaching down towards the foot.
The posture is one of those powerful asnanas where the body (the gross and subtle) is active with energy moving in two directions: uplifting and grounding. In mystic traditions a triangle symbolizes the transformation of low energies into higher ones and the condensation of higher energies and their embodiment on the gross level, which indicates the oneness of gross and subtle.