I don't know where you study. At that time, the topics should only be these kinds of my previous books that I read myself. I hope the textbook hasn't changed too much. I'm only high 1. . . You have to pay for your hard work. . (1) Let m be an even number, n an odd number, m! ! Male (male 2) (male 4) ... 2, n! ! N(n-2)(n-4)… 1, for example: 10! ! = 10× 8×6×4×2,9! ! =9×7×5×3× 1, then 19! ! Use 98! ! There are () 0 (a) 9 (b)1(c)12 (d)13 (2) A workshop can produce 120 pieces of Class A parts every day.1. Suppose the number of sets produced is 3x/120+2x/100+x/200 = 30x = 600, the number of days to produce A is 600*3/ 120= 15, and the number of days to produce B is 600 * 2.

(4) In triangle ABC, angle C=90 degrees, AC=4, BC=3, with point C as the center and r as the radius. If circle C intersects with AB, find the distance angle R = 90 degrees, AC=4, BC=3, then AB=5 finds the minimum value of the sum of the radii of circles with the height of 12/5 in AB. The maximum radius is the length of AC, that is, 4. At this point, the circle intersects the AB edge at point A .. so the range of R is 12/5 [5]. In right-angle ABCD, e is the midpoint of AD, EF passes through AB and F vertically, and connecting FC (AB > BC) (1) proves whether △AEF∽△DCE (2)△AEF and △EFC know each other. If they know each other, they know each other. If you don't know, please explain why (3) If AB/BC = K, is there such a K that △AEF and △BFC know each other? If yes, find the value of k; If not, please explain why.