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Question Number 214297 by ajfour last updated on 04/Dec/24

Commented by ajfour last updated on 04/Dec/24

the tangents are at right angles to  one another and corner maynot be  at semicircle centre.

thetangentsareatrightanglestooneanotherandcornermaynotbeatsemicirclecentre.

Commented by mr W last updated on 05/Dec/24

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Commented by ajfour last updated on 05/Dec/24

https://youtu.be/ys6xN29xNUM?si=9rk6nXD0GcmHTp9Z

Answered by mr W last updated on 04/Dec/24

Commented by mr W last updated on 06/Dec/24

a=1  R=3  b=r  (b/(tan (β/2)))=x+(√((R−b)^2 −b^2 ))=x+(√(R^2 −2Rb))  ⇒tan (β/2)=(b/(x+(√(R^2 −2Rb))))  similarly  ⇒tan (α/2)=(a/(−x+(√(R^2 −2Ra))))  (β/2)=(π/4)−(α/2)  tan (β/2)=((1−tan (a/2))/(1+tan (a/2)))  (b/(x+(√(R^2 −2Rb))))=((1−(a/(−x+(√(R^2 −2Ra)))))/(1+(a/(−x+(√(R^2 −2Ra))))))  (b/(x+(√(R^2 −2Rb))))=((−x+(√(R^2 −2Ra))−a)/(−x+(√(R^2 −2Ra))+a))  let α=(a/R), β=(b/R), ξ=(x/R)  (β/(ξ+(√(1−2β))))=((−ξ+(√(1−2α))−α)/(−ξ+(√(1−2α))+α))  let λ=(√(1−2β)), p=(√(1−2α))+α, q=(√(1−2α))−α  ((1−λ^2 )/(2(ξ+λ)))=((q−ξ)/(p−ξ))  (p−ξ)λ^2 +2(q−ξ)λ+(2q+1)ξ−[2ξ^2 −(2q+1)ξ+p]=0  λ=((ξ−q+(√((ξ−q)^2 +(p−ξ)[2ξ^2 −(2q+1)ξ+p])))/(p−ξ))  b={1−{((ξ−q+(√((ξ−q)^2 +(p−ξ)[2ξ^2 −(2q+1)ξ+p])))/(p−ξ))}^2 }(R/2)  b_(max) ≈0.66471561 at ξ=(x/R)≈−0.14031961  =================

a=1R=3b=rbtanβ2=x+(Rb)2b2=x+R22Rbtanβ2=bx+R22Rbsimilarlytanα2=ax+R22Raβ2=π4α2tanβ2=1tana21+tana2bx+R22Rb=1ax+R22Ra1+ax+R22Rabx+R22Rb=x+R22Raax+R22Ra+aletα=aR,β=bR,ξ=xRβξ+12β=ξ+12ααξ+12α+αletλ=12β,p=12α+α,q=12αα1λ22(ξ+λ)=qξpξ(pξ)λ2+2(qξ)λ+(2q+1)ξ[2ξ2(2q+1)ξ+p]=0λ=ξq+(ξq)2+(pξ)[2ξ2(2q+1)ξ+p]pξb={1{ξq+(ξq)2+(pξ)[2ξ2(2q+1)ξ+p]pξ}2}R2bmax0.66471561atξ=xR0.14031961=================

Commented by mr W last updated on 06/Dec/24

Commented by ajfour last updated on 06/Dec/24

(a/(R−a))=sin θ  (R−a)cos θ=acot (α/2)+x  R+x=bcot (β/2)  (α/2)+(β/2)=(π/4)  ((A+B)/(1−AB))=1   [  for  ((tan (α/2)+tan (β/2))/(1−tan (α/2)tan (β/2)))=1]  A+B=1−AB  (a/((R−a)cos θ−x))+(b/(R+x))         +((ab)/((R+x){(R−a)cos θ−x}))=1  or  a(R+x)+b(R−a)cos θ−bx+ab    +x^2 +{R−(R−a)cos θ}x−R(R−a)cos θ=0  or  x^2 +{a−b+R−(R−a)cos θ}x+a(b+R)         +(b−R)(R−a)cos θ=0  diff.  2x+{a−b+R−(R−a)cos θ}=0  or (R−a)cos θ−x=R+x+a−b  x=((b−a−R+(R−a)cos θ)/2)  b{(1/(R+x))+(a/((R+x){(R−a)cos θ−x))}     =1−(a/({(R−a)cos θ−x}))

aRa=sinθ(Ra)cosθ=acotα2+xR+x=bcotβ2α2+β2=π4A+B1AB=1[fortanα2+tanβ21tanα2tanβ2=1]A+B=1ABa(Ra)cosθx+bR+x+ab(R+x){(Ra)cosθx}=1ora(R+x)+b(Ra)cosθbx+ab+x2+{R(Ra)cosθ}xR(Ra)cosθ=0orx2+{ab+R(Ra)cosθ}x+a(b+R)+(bR)(Ra)cosθ=0diff.2x+{ab+R(Ra)cosθ}=0or(Ra)cosθx=R+x+abx=baR+(Ra)cosθ2b{1R+x+a(R+x){(Ra)cosθx}=1a{(Ra)cosθx}

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