maths question
2012-07-30 4:06 am
圖片參考：http://imgcld.yimg.com/8/n/HA00517423/o/701207290051813873413280.jpg
in the figure,o is the centre of the circle.AC and BD are chords intersecting at E such that BE=CE.
1.SHOW THAT A,E, O AND B ARE CONCYCLIC.
回答 (1)
2012-08-05 1:34 am
✔ 最佳答案
1)∠CAB = (1/2)∠COB (∠at centre twice ∠ at ☉ce)
Let M be the mid point of BC , then OM ⊥ BC and EM ⊥ BC since EM is the height of isos.△ BEC , so EOM is a straight line
So ∠BOM = (1/2)∠COB =∠CAB ,
therefore A,E ,O AND B ARE CONCYCLIC. (ext.∠= int. opp.∠)
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