In △ ABC, ∠ C = 90 ° and the intersection line BC of AB is at D. if ∠ bad - ∠ DAC = 22.5 °, then the degree of ∠ B is______ .
∵ De is the vertical bisector of AB, ∵ ad = BD, ∵ B = ∵ DAB, ∵ ACB = 90 °, and ∵ B + ∵ BAC = 90 °, which can be divided into two cases: ① as shown in Figure 1, ∵ B + ∵ BAC = 90 °, bad -
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- 1. It is known that in △ ABC, points D, e and F are points on BC, AB and AC respectively, AF is parallel to ED, and AF = ed, extend FD to point G, so that DG = FD, and verify that ED and Ag are equally divided,
- 2. (1 / 3) the known triangles ABC, (|) BD and CE are bisectors of angle B and angle c, respectively. Through point a, make AF vertical BD, Ag vertical CE, the perpendicular feet are f, G, connecting FG (1 / 3) the known triangles ABC, (|) BD and CE are bisectors of angle B and angle c, respectively. Through point a, make AF vertical BD, Ag vertical CE, and the perpendicular feet are f, G, connecting FG. (2) if C
- 3. In ABC, BD is the inner bisector of angle B, CE is the outer bisector of angle c, AF is perpendicular to BD, Ag is perpendicular to CE, FG and ABC?
- 4. As shown in the figure, BD is the extension of the intersection of the middle line AE ⊥ BD on the edge AC of △ ABC at the point ECF ⊥ BD. be + BF. = 2bd is proved at the point F It's sloppy
- 5. As shown in the figure, in △ ABC, BD and CD divide ∠ ABC and ∠ ACB equally, and try to explain ∠ d = 90 ° + & # 189; ∠ a
- 6. In the triangle ABC, BD.CD They are the diplomatic bisector of angle ABC and angle ACB
- 7. In triangle ABC, AF: FB = BD: DC = Ce: AE = 3:2, be, CF and ad intersect point igh on BC, AC and ab respectively, and the area of IgH is 1
- 8. As shown in the figure, in △ ABC, ∠ B = 90 °, ab = 3, AC = 5, fold △ ABC so that point C coincides with point a, and the crease is De, then the perimeter of △ Abe is______ .
- 9. It is known that: as shown in the figure, point D is a point on the edge AC of △ ABC, passing point D makes de ⊥ AB, DF ⊥ BC, e and F are perpendicular feet, then passing point D makes DG ∥ AB, intersecting BC at point G, and de = DF. (1) prove: DG = BG; (2) prove: BD bisects EF vertically
- 10. RT, in triangle ABC, ab = AC = 10, point D on BC, de parallel AC, DF parallel AB, find the perimeter of quadrilateral AEDF
- 11. In △ ABC, the vertical bisectors of AB and AC intersect BC at points E and f respectively. If ∠ BAC = 115 °, then ∠ EAF=______ Degree
- 12. If the inscribed circle of RT triangle is tangent to the hypotenuse AB at D, and ad = 1, BD = 2, then s ABC =? AB is the hypotenuse If the inscribed circle of RT triangle and hypotenuse AB are tangent to D, and ad = 1, BD = 2, then s ABC =? AB is hypotenuse How to use area
- 13. As shown in the figure, in △ ABC, ab = AC, ∠ BAC = 80 °, point P is within △ ABC, ∠ PBC = 10 °, PCB = 30 °, calculate the degree of ∠ BAP What are you doing?
- 14. In △ ABC, ab = AC, ∠ BAC = 80 ° and P is a point in △ ABC, so that the angle PBC = 10 ° and ∠ PCA = 20 °. Find the degree of ∠ PAC
- 15. As shown in the figure, we know that the side length of equilateral triangle ABC is 3, M is a point on AC, passing through point m, make me parallel AB, intersect BC at point E, make MF ⊥ AB at point F, let AF = x, the median line length of trapezoidal emfb is y, find out the function analytic formula of Y and X, and write out the value range of X
- 16. AB = ad ∠ ABC = ∠ ADC, AC and BD intersect at point O. it is proved that AC is the vertical bisector of BD
- 17. Each vertex of the triangle ABC makes a parallel line AD / / be / / FC, which intersects with the extension of BC, Ca and BA at points D, e and f respectively Prove s triangle def = s double triangle ABC
- 18. As shown in the figure, △ ABC is an equilateral triangle, the bisectors of ∠ ABC and ∠ ACB intersect at O, Bo and Co, and the vertical bisectors of CO intersect at e and F As shown in the figure, △ ABC is an equilateral triangle, the bisectors of ∠ ABC and ∠ ACB intersect at points o, Bo and Co, the vertical bisectors of BC intersect at points E and F, and the perpendicular feet are m and N respectively
- 19. In the quadrilateral ABCD, point O is the midpoint of CD, Ao and Bo bisect ∠ DAB, ∠ ABC, ∠ AOB = 120 ° respectively, and prove AD + Half DC + BC = ab
- 20. Is a axisymmetric figure