As shown in the figure, points a and B are on the straight line Mn, ab = 8cm, and the radii of ⊙ A and ⊙ B are 1cm ⊙ a moves from left to right at the speed of 2cm per second. At the same time, the radius of ⊙ B is also increasing. The relationship between the radius R (CM) and the time t (seconds) is r = 1 + T (t ≥ 0). (1) try to write the functional expression between the distance d between points a and B and the time t (seconds). (2) ask how many seconds after point a starts, the two circles are tangent

As shown in the figure, points a and B are on the straight line Mn, ab = 8cm, and the radii of ⊙ A and ⊙ B are 1cm ⊙ a moves from left to right at the speed of 2cm per second. At the same time, the radius of ⊙ B is also increasing. The relationship between the radius R (CM) and the time t (seconds) is r = 1 + T (t ≥ 0). (1) try to write the functional expression between the distance d between points a and B and the time t (seconds). (2) ask how many seconds after point a starts, the two circles are tangent

According to the title: if OA is on the right side of ob, then the speed of OA is greater than the radius growth speed of ob, and it can never be tangent. Therefore, OA is on the left side of ob. 1. Point B is the fixed point, point a is the moving point, and the speed of point a is 2cm / s, so the distance of point a is s = 2T, and the distance of point AB is 8cm, which needs 8 / 2 = 4 seconds

As shown in the figure, points a and B are on the straight line Mn, ab = 11cm, and the radii of ⊙ A and ⊙ B are all 1cm. ⊙ a moves from left to right at the speed of 2cm per second. At the same time, the radius of ⊙ B is also increasing. The relationship between the radius R (CM) and time t (s) is r = 1 + T (t ≥ 0)
(1) Try to write out the functional expression between the distance D (CM) between points a and B and the time t (s). (2) ask how many seconds after point a starts, the two circles are tangent?

(1) When 0 ≤ t ≤ 5.5, point a is on the left side of point B, and the function expression is d = 11-2t; when T & gt; 5.5, point a is on the right side of point B, and the distance between the center of the circle is equal to the distance taken by point a minus 11, then the function expression is d = 2t-11; (2) four cases are considered: two circles are tangent, which can be divided into the following four cases: 1

It is known that there are two points B and C on the line ad. in a certain line ad = 16cm, BC = 7cm, and points E and F are the midpoint of the line CD and ab respectively. The length of the line EF is calculated
As shown in the figure:
.__ .__ ._________ .__ .__ .
A F B C E D

AD-BC=AB+CD 16-7=9