If vector AP = 1 / 3 vector Pb and vector AB = Λ vector BP, then the value of Λ is?

If vector AP = 1 / 3 vector Pb and vector AB = Λ vector BP, then the value of Λ is?

-4/3
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As shown in the figure, points a and B are two points on ⊙ o, ab = 10, and point P is the moving point on ⊙ o (P does not coincide with a and b). Connecting AP, Pb and passing point O, make OE ⊥ AP on E and of ⊥ Pb on F respectively, then the length of EF is ()
A. 3B. 4C. 5D. 6

∵ point P is a moving point on ⊙ o (P does not coincide with a and b), OE ⊥ AP is in E, of ⊥ Pb is in F, ∵ according to the vertical diameter theorem, ∵ AE = EP, BF = PF, that is, e is the midpoint of AP, f is the midpoint of Pb, ∵ EF is the △ APB median line; ab = 10, ∵ EF = 12ab = 12 × 10 = 5 (triangle median line theorem); so select C

As shown in the figure, points a and B are two points on ⊙ o, ab = 10, and point P is the moving point on ⊙ o (P does not coincide with a and b). Connecting AP, Pb and passing point O, make OE ⊥ AP on E and of ⊥ Pb on F respectively, then the length of EF is ()
A. 3B. 4C. 5D. 6

∵ point P is a moving point on ⊙ o (P does not coincide with a and b), OE ⊥ AP is in E, of ⊥ Pb is in F, ∵ according to the vertical diameter theorem, ∵ AE = EP, BF = PF, that is, e is the midpoint of AP, f is the midpoint of Pb, ∵ EF is the △ APB median line; ab = 10, ∵ EF = 12ab = 12 × 10 = 5 (triangle median line theorem); so select C

As shown in the figure, points a and B are two points on ⊙ o, ab = 10, and point P is the moving point on ⊙ o (P does not coincide with a and b). Connecting AP, Pb and passing point O, make OE ⊥ AP on E and of ⊥ Pb on F respectively, then the length of EF is ()
A. 3B. 4C. 5D. 6

∵ point P is a moving point on ⊙ o (P does not coincide with a and b), OE ⊥ AP is in E, of ⊥ Pb is in F, ∵ according to the vertical diameter theorem, ∵ AE = EP, BF = PF, that is, e is the midpoint of AP, f is the midpoint of Pb, ∵ EF is the △ APB median line; ab = 10, ∵ EF = 12ab = 12 × 10 = 5 (triangle median line theorem); so select C