During the parade on a square yard, one yard divided into 2 equal triangles with a strip of silk. A person at the top of the silk Strip start entering in the courtyard, with the direction of silk strips at an angle of 30 degrees. As to the other side of the pitch, people continue to move to the strip of silk to the direction perpendicular to the strip of silk. Ask a new trend with the pitch has just left a sharp corner?
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