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Chongqing Nankai Middle School 20 13 Ninth Grade Last Term Final Exam Mathematics Examination Paper
Answer 26 questions:

1) When BG = FC, G F is the bisector because FC=EF=FG. FC/BC=EC/AC= 1:3 AC takes 2 seconds to walk 6 and 1/3.

2) at t, gf = ef = EC = ts =1/2gf * ef * sin120 = √ 3/4 * T2 (a quarter root 3 times the square of t).

At t, s =1/2 * ef * eg * sin30 =1/2 * t * √ 3 (6-t) *1/2 = √ 3/4 * t (6-t).

At t[6, 12], s is a quadrilateral, which is the difference between the areas of two triangles. s = 1/2 *√3(t-6)* 6 * SIN 30- 1/2 *(t-6)*√3/2(t

3) The triangle BCN and ACM are congruent, so AM=BN, so AM+AN is a fixed value of 6, the circumference of AMN is 6+MN, and MN is equal to MC (equilateral triangle). The minimum value of MC is that when A C is perpendicular to AD, MC is the distance from C to AD of 3√3, so the minimum circumference of AMN is 6+3√3, which is achieved after rotating 30.