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1) 圖: http://us.f6.yahoofs.com/hkblog/njLcOQ6FBRQYG13ZuCFh6Q--_1/blog/20090825050138565.jpg?ib_____DM.CMM6Twfind the value of a2)圖: http://us.f6.yahoofs.com/hkblog/njLcOQ6FBRQYG13ZuCFh6Q--_1/blog/20090825050611607.jpg?ib_____DQTjCMUHMIn the figure , AE=AF and DG//HK .Find (a)∠AEF and... 顯示更多 1) 圖: http://us.f6.yahoofs.com/hkblog/njLcOQ6FBRQYG13ZuCFh6Q--_1/blog/20090825050138565.jpg?ib_____DM.CMM6Tw find the value of a 2)圖: http://us.f6.yahoofs.com/hkblog/njLcOQ6FBRQYG13ZuCFh6Q--_1/blog/20090825050611607.jpg?ib_____DQTjCMUHM In the figure , AE=AF and DG//HK .Find (a)∠AEF and ∠AFE; (b)∠AIJ;and (c)AJK. 3)圖: http://us.f6.yahoofs.com/hkblog/njLcOQ6FBRQYG13ZuCFh6Q--_1/blog/20090825051149869.jpg?ib_____D_2iNR2xD In the figure ,ABCDEF is a regular hexagon and△DEG is an equilateral triangle . a)find ∠GED and∠CDE b)Is EG //CD ? Give a reason. 更新: 係用中2的方法計算

最佳解答:

1) The five angles are the exterior angles of the pentagon. Sum of exterior angles of a polygon = 360 a + a + 10 + a + 20 + a + 30 + 80 = 360 4a + 140 =360 4a = 220 a = 55 2) (a) Since AE = AF, triangle AEF is isoceles. angle∠AEF = angle ∠AFE = (180 – 30) / 2 = 75 (b) Since DG//HK, angle∠AIJ = angle∠AEF = 75 (corresponding angles) (c) Similarly angle∠AJI =75. angle∠AJK = 180 – angle∠AJI = 105 3) (a) Since DEG is an equilateral triangle, angle∠GED = 180 / 3 = 60 Sum of interior angles of a hexagon = (6 – 2)x 180 = 720 angle∠CDE = 720 / 6 = 120 (b) Since angle∠CDE + angle∠GED = 120 + 60 = 180, EG // CD (interior angles of parallel lines)

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