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As shown in the figure, it is known that ﹥ 1 = ﹥ ABC = ﹥ ADC, ﹥ 3 = ﹥ 5, ﹥ 2 = ﹥ 4, ﹥ ABC + ﹥ BCD = 180 degree Ten questions on 10 pages of tiantiantong Modu -- (1) Verify AD / / BC (2) Verification AB / / CD
As shown in the figure, it is known that ∵ 1 = ∵ ABC = ∵ ADC, ∵ 3 = ∵ 5, ∵ 2 = ∵ 4, ∵ ABC + ∵ BCD = 180 °. Complete the following reasoning process: (1) ∵ 1 = ∵ ABC (known), ∵ ad ∥ bcbc (equal position angle, two parallel lines, equal position angle, two parallel lines) (2) ∵ 3 = ∵ 5 (known), ∵ ab ∥ cdcd
As shown in the figure, AB parallel CD, be bisector angle ABC, de bisector angle ADC angle bad = 70 degrees (1) calculate the degree of EDC
(2) If the angle BCD = 40 degrees, try to find the degree of the angle bed
Ab ‖ CD shows that ∠ bad and ∠ ADC are complementary angles, i.e., ∠ bad + ∠ ADC = 180 degree
So ∠ ADC = 180 ° - 70 ° = 110 °
Because of the de bisector angle ADC, EDC = 1 / 2 and ADC = 55 degrees
Angle BCD = 40 degrees, the same can be obtained ∠ CBE = 70 degrees
The sum of the internal angles of the quadrilateral is 360 degrees, so ∠ bed = 360-70-55-40 = 195 degrees
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