In the triangle ABC, the angle ACB = 90 degrees, AC = BC, M is a point in the triangle ABC, and am = 3, BM = 1, CM = 2

In the triangle ABC, the angle ACB = 90 degrees, AC = BC, M is a point in the triangle ABC, and am = 3, BM = 1, CM = 2

120°

As shown in the figure, in △ ABC, BD bisects ∠ ABC, and BD ⊥ AC intersects D, de ∥ BC intersects AB at E. AB = 5cm, AC = 2cm, then the perimeter of △ ade=______ cm．

∵ DB bisects ∵ ABC, ∵ abd = ∵ CBD; ∵ BD ⊥ AC, i.e. ∵ ADB = ∵ CDB = 90 °, ∵ a = ∵ C, i.e. △ ABC is isosceles triangle; ∵ D is the midpoint of AC, i.e. ad = 12ac = 1cm; ∵ de ∥ BC, ∵ EDB = ? CBD; also ? abd = ? CBD, ? EBD = ∵ EDB, i.e. be = de; ? the week of

As shown in the figure, in △ ABC, BD bisects ∠ ABC, and BD ⊥ AC intersects D, de ∥ BC intersects AB at E. AB = 5cm, AC = 2cm, then the perimeter of △ ade=______ cm．

∵ DB bisects ∵ ABC, ∵ abd = ∵ CBD; ∵ BD ⊥ AC, i.e. ∵ ADB = ∵ CDB = 90 °, ∵ a = ∵ C, i.e. △ ABC is isosceles triangle; ∵ D is the midpoint of AC, i.e. ad = 12ac = 1cm; ∵ de ∥ BC, ∵ EDB = ∵ CBD; and ∵ abd = ∵ CBD, ∵ EBD = ∵ EDB, i.e. be = de; ? ade perimeter = AD + de + AE = AD + AE + be = AD + AB = 1 + 5 = 6cm

Triangle ABC is equilateral triangle, angle 1 is equal to angle 2, angle 3 is equal to angle bec

If the middle is an equilateral triangle, then the angle BCE plus angle 3 is equal to 60 degrees. Because the middle is an equilateral triangle, then the angle fed plus angle BEC is 180 degrees, the angle Fed is 60 degrees, and the angle BEC is 120 degrees