shape數學問題(10點)help~helpso easy－百科全書

標題:

shape數學問題(10點)help~helpso easy

發問:

1.In the figure, AB=DC=3cm and ∠BAC=∠dca=23°.Are△ABC and △CDA congruent? if they are, give the reason. 圖片參考：http://imgcld.yimg.com/8/n/HA05896895/o/701103060068613873387310.jpg 2. In the figure, ADB is a straight line,AC=BC=7cm and ∠ADC=90°.Are△ADC and △BDC congruent? if they are, give the reason. ... 顯示更多 1.In the figure, AB=DC=3cm and ∠BAC=∠dca=23°.Are△ABC and △CDA congruent? if they are, give the reason. 圖片參考：http://imgcld.yimg.com/8/n/HA05896895/o/701103060068613873387310.jpg 2. In the figure, ADB is a straight line,AC=BC=7cm and ∠ADC=90°.Are△ADC and △BDC congruent? if they are, give the reason. 圖片參考：http://imgcld.yimg.com/8/n/HA05896895/o/701103060068613873387311.jpg 3.In the figure, AB=DC=6cm,∠A=30°,∠B=25°,∠D=30°and ∠COD=125° (a) find ∠C and∠AOB (b)Are△AOB and △DOC congruent? If they are, give the reason. 圖片參考：http://imgcld.yimg.com/8/n/HA05896895/o/701103060068613873387322.jpg 全部要prove!! 要有算式!!

最佳解答:

1 AB = CD (given) ∠BAC = ∠ACD = 30° (Given) AC = AC (same side) △ABC congruent to △CDA (SAS) 2 CD = CD (same side) ∠ADC = ∠BDC = 90° (Right-angle) AC = BC (Given) △ADC congruent to △BDC (RHS) 3(a) ∠C = 180° - 125° - 30° = 25° ∠AOB = 125° (b) AB = CD (Given) ∠A = ∠D = 30° (Given) ∠B = ∠C = 25° (Proved) △AOB congruent to △DOC (ASA)