As shown in the figure, point AB is on the straight line Mn, ab = 13, circle a, radius of circle B is 1, circle a moves from left to right along the straight line Mn at the speed of 3 per second, in the process of circle a's movement, its radius is 1 At the same time, circle B moves along the straight line Mn from right to left at the speed of 1 per second, and its radius remains the same. (1) try to write the functional relationship between the distance d between points AB and time T. (2) how long does circle a and circle B move and how many times are two circles tangent

As shown in the figure, point AB is on the straight line Mn, ab = 13, circle a, radius of circle B is 1, circle a moves from left to right along the straight line Mn at the speed of 3 per second, in the process of circle a's movement, its radius is 1 At the same time, circle B moves along the straight line Mn from right to left at the speed of 1 per second, and its radius remains the same. (1) try to write the functional relationship between the distance d between points AB and time T. (2) how long does circle a and circle B move and how many times are two circles tangent

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