As shown in the figure, in △ ABC, ab = AC = 12cm, De is the vertical bisector of AB, intersecting AB, AC at D and e respectively. (1) if ∠ C = 70 °, calculate the degree of ∠ BEC; (2) if the perimeter of △ ABC is 30cm, calculate the perimeter of △ BCE

As shown in the figure, in △ ABC, ab = AC = 12cm, De is the vertical bisector of AB, intersecting AB, AC at D and e respectively. (1) if ∠ C = 70 °, calculate the degree of ∠ BEC; (2) if the perimeter of △ ABC is 30cm, calculate the perimeter of △ BCE

(1) ∵ AB = AC, ∵ ABC = ∵ C = 70 °, ∵ a = 180 ° - ∵ ABC - ∵ C = 40 °, ∵ De is the vertical bisector of AB, ∵ AE = be, ∵ Abe = ∵ a = 40 °, ∵ BEC = ∵ a + ∵ Abe = 80 °; (2) ∵ in △ ABC, ab = AC = 12cm, ∵ ABC = (AB + AC + BC) - (AB + AC) = 30 - (12 + 12) = 6 (CM), ∵ BCE is: be + CE + BC = AE + CE + BC = AC + BC = 12 + 6 = 18 (CM) The perimeter of the ∧ BCE is 18 cm