If ∠ BDC = α + 2 / 3 ∠ a, α is obtained
The results show that: DBC = 2 ∠ abd, DCB = 2 ∠ ACD, BDC = α + 2 / 3 ∠ a, a = 180 - ∠ ABC - ∠ ACB = 180-1.5 ∠ dbc-1.5 ∠ DCB ∠ BDC = 180 - ∠ DBC - ∠ DCB, and BDC = α + 2 / 3 ∠ a = α + 2 / 3 (180-1.5 ∠ dbc-1.5 ∠ DCB) = α + 120 - ∠ DBC - ∠ DCB, so α = 60
RELATED INFORMATIONS
- 1. Known: as shown in the figure, ∠ abd = ∠ DBC, ∠ ACD = ∠ DCE. (1) if ∠ a = 50 °, find the degree of ∠ D; (2) guess the relationship between ∠ D and ∠ a, and explain the reason; (3) if CD ‖ AB, judge the relationship between ∠ ABC and ∠ a
- 2. If ∠ BDC = x + 2 / 3 ∠ a, find the degree of X?
- 3. In the parallelogram ABCD, AE bisection ∠ DAB intersects DC with E, BF bisection ∠ ABC intersects DC with F, DC = 8cm, ad = 3cm, find the length of De, DF and FC RT
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- 6. As shown in the figure, in the triangle ABC, < a = 55 ° and H is the intersection of high BD and EC, then < BHC=
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- 14. As shown in figure a, CE / / AB, so ∠ 1 = 2 = B, so ∠ ACD = 1 + ∠ 2 = a + B, which is a useful conclusion, In the quadrilateral ABCD of figure B, do AE / / BC to intersect DC with e through A. if you have this conclusion, find the degree of ∠ a + ∠ B + ∠ C + ∠ D Figure a http://hiphotos.baidu.com/yalijudy/pic/item/099efed1bbb16a299a50274f.jpg Figure B http://hiphotos.baidu.com/yalijudy/pic/item/6750e5f54b044b34bd3109e2.jpg
- 15. AE bisection BAC.CE Divide ∠ ACD equally (1) if AB / / CD, judge whether △ ace is a right triangle, please explain the reason; (2) if ace is a right triangle AE bisection BAC.CE Bisecting ∠ ACD (1) If AB / / CD, judge whether △ ace is a right triangle, please explain the reason; (2) If the triangle ace is a right triangle, judge whether the line AB is parallel to the line CD, please explain the reason
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- 17. Known: as shown in the figure, in △ ABC, ab = AC, ad bisects ∠ BAC, CE ⊥ AB in E, intersects ad in F, AF = 2CD, find the degree of ∠ ace
- 18. As shown in the figure, in the isosceles triangle ABC, ∠ B = 90, ab = BC = 4cm, point P moves from point a to B at the speed of 1m / s, At the same time, point Q moves from point B to point C at a speed of 2 m / s (1) Which point will arrive first? (2) Let the area of triangle ACB be Y1 and the area of triangle qAB be Y2 after X minutes (3) When the moving time is in what range: (1) the area of triangle PCB is larger than that of triangle; (2) the area of triangle PCB is smaller than that of triangle qAB? Picture too late to pass, sorry!
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