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It is known that AB is the diameter of circle O, the chord center distance of chord BC is 4, then the length of AC is? Do me a favor
Angle ACB = 90 degrees,
4:AC=BO:AB,
AC=4*AB/BO=4*AB/(AB/2)
AC=8.
As shown in the figure, AB is the diameter of the circle O, the chord BC is equal to 2cm, and the angle ABC is equal to 60 degrees
(1) ∵ AB is the diameter of ⊙ o, ∵ ACB = 90 °, ∵ ABC = 60 °, ∵ BAC = 180 ° - ACB - ABC = 30 °, ∵ AB = 2BC = 4, that is, the diameter of ⊙ o is 4cm; (2) connect OC, as shown in figure (1), then OC = ob, ∵ CD ⊥ Co, ∵ OCD = 90 °, ∵ BAC = 30 °, ∵ cod = 2 ∵ BAC = 60 °, ∵
As shown in the figure, in △ ABC, the circle O with BC as the chord intersects AB at point D
Intersection AC at point E, BD = CE, ab = AC
∵ BD = CE, ∵ arc BD = arc CE,
That is, arc BDE = arc CED,
Therefore, ab = AC
As shown in the figure, AB is the diameter of ⊙ o, the chord BC, OD ⊥ BC is made through point B, and the perpendicular foot is e. if BC = 8cm, ∠ ABC = 30 °, the length of De is ()
A. 23B. 43C. 433D. 833
As shown in the figure, connecting AC. ∵ AB is the diameter of ⊙ o (known), ∵ C = 90 ° (the circumferential angle of diameter is right angle), ∵ OD ⊥ BC (known), ∵ BeO = ∵ C = 90 °, ∵ OD ∥ AC (the same angle, two lines are parallel), point O is the midpoint of line AB, ∵ OE is the median line of △ ABC, ∵ OE = 12ac. ∵ in right angle △ ABC, BC = 8cm, ∵ ABC = 30 °, AC = BC ∵ Tan ∵ ABC= 8 × 33 = 833 (CM), AC = 12ab = OA = OD, ed = od-oe = ac-oe = 12ac = 433 (CM)
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