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Question Number 201659 by LimPorly last updated on 10/Dec/23

Find the shortest distance between   point A(3,2) and curve y=(√x) (x>0).

FindtheshortestdistancebetweenpointA(3,2)andcurvey=x(x>0).

Answered by mr W last updated on 10/Dec/23

say the distance is s.  say the point on the curve is (p^2 , p)  Φ=s^2 =(p^2 −3)^2 +(p−2)^2   (dΦ/dp)=4p(p^2 −3)+2(p−2)=0  p^3 −((5p)/2)−1=0  ⇒p=((√(30))/3) sin ((π/3)+(1/3)sin^(−1) ((3(√(30)))/(25)))  s_(min) =(√(13−((75)/9) sin^2  ((π/3)+(1/3)sin^(−1) ((3(√(30)))/(25)))−(√(30)) sin ((π/3)+(1/3)sin^(−1) ((3(√(30)))/(25))) ))       ≈0.257 552 568

saythedistanceiss.saythepointonthecurveis(p2,p)Φ=s2=(p23)2+(p2)2dΦdp=4p(p23)+2(p2)=0p35p21=0p=303sin(π3+13sin133025)smin=13759sin2(π3+13sin133025)30sin(π3+13sin133025)0.257552568

Commented by mr W last updated on 10/Dec/23

Commented by LimPorly last updated on 10/Dec/23

Thank you sir

Thankyousir

Answered by mr W last updated on 11/Dec/23

y=x^2   A(2,3)  P(p,p^2 )  tan θ=2p  2=p+r sin θ   ...(i)  3=p^2 −r cos θ  ...(ii)  r^2 =(2−p)^2 +(p^2 −3)^2   ((2−p)/(p^2 −3))=2p  p^3 −((5p)/2)−1=0  ⇒p=((√(30))/3) sin ((π/3)+(1/3)sin^(−1) ((3(√(30)))/(25)))

y=x2A(2,3)P(p,p2)tanθ=2p2=p+rsinθ...(i)3=p2rcosθ...(ii)r2=(2p)2+(p23)22pp23=2pp35p21=0p=303sin(π3+13sin133025)

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