The length of equilateral △ ABC side is 8, D is a moving point on AB side, passing through D as de ⊥ BC at point E, passing through e as EF ⊥ AC at point F. (1) if ad = 2, find the length of AF; (2) when ad takes what value, de = EF
(1) ∵ AB = 8, ad = 2 ∵ BD = ab-ad = 6, in RT △ BDE ∵ BDE = 90 ° - ∵ B = 30 ° ∵ be = 12bd = 3 ∵ CE = bc-be = 5, in RT △ CFE ∵ CEF = 90 ° - ∵ C = 30 ∵ CF = 12ce = 52 ∵ AF = ac-fc = 112; (2) in △ BDE and △ EFC ∵ bed = ∵ CFE = 90 ∵ B = ∵ CDE = EF, ? B ?
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- 5. The middle angle of the triangle ABC is ACB = 90 ° and D is on the extension line of BC. Eg bisects vertically, BD intersects AB on e, BD intersects g, de intersects AC on F. find: e is on the vertical bisector of AF
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- 7. As shown in the figure, in the triangle ABC, the angle ACB is equal to 90 degrees. D is a point on the extension of BC. E is the intersection of the vertical bisector of BD with ab. de intersects AC with F Prove that e bisects AF vertically
- 8. As shown in the figure, in the triangle ABC, the angle ACB = 90 degrees, D is a point on the BC extension line, e is the intersection of BD vertical bisector and AB, and de intersects AC at point F Verification: point E is also on the vertical bisector of AF
- 9. As shown in the figure, it is known that in △ ABC, ∠ ACB = 90 °, D is a point on the extension line of BC, e is a point on AB, and it is on the vertical bisector eg of BD, When De is intersected with AC in F, AE = EF
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