In (acute) triangle ABC, angle c = 90 degrees, angle CBA = 30 degrees, BC = 20 √ 3. (1) find the length of BC (2) A circle with a radius of 6 moves to the right at the speed of 2 unit lengths per second. During the movement, the center of the circle is always on the straight line ab. Q: how many seconds does the circle tangent to the straight line on one side of the triangle ABC

（1）AB= 40,AC=20,BC=20√3
(2) 14 seconds later

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