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Question Number 170202 by otchereabdullai@gmail.com last updated on 18/May/22

 A point is 3cm, 4cm and 5cm away     from three vertices of a rectangle.    How far can it be from the 4th vertex.    Find all solutions

Apointis3cm,4cmand5cmawayfromthreeverticesofarectangle.Howfarcanitbefromthe4thvertex.Findallsolutions

Commented by otchereabdullai@gmail.com last updated on 18/May/22

much much grateful thanks

muchmuchgratefulthanks

Commented by mr W last updated on 18/May/22

there are infinitely many solutions.

thereareinfinitelymanysolutions.

Commented by MJS_new last updated on 18/May/22

it′s either 0∨3(√2)∨4(√2)

itseither03242

Commented by otchereabdullai@gmail.com last updated on 18/May/22

please help me with some of the   solutions prof W

pleasehelpmewithsomeofthesolutionsprofW

Commented by otchereabdullai@gmail.com last updated on 18/May/22

prof mjs how did you get the   0∨3(√2)∨4(√2)

profmjshowdidyougetthe03242

Commented by MJS_new last updated on 18/May/22

“fix” the vertices  A= ((0),(0) )     B= ((a),(0) )     C= ((a),(b) )     D= ((0),(b) )  let P= ((p),(q) )  equations with α, β, γ unknown at first  (1)     ∣AP∣^2 =α^2   (2)     ∣BP∣^2 =β^2   (3)     ∣CP∣^2 =γ^2   (4)     ∣DP∣^2 =x^2   you can easily solve the system for p, q and  get a formula for x^2 . now insert all possible  permutations of 3, 4, 5 for α, β, γ

fixtheverticesA=(00)B=(a0)C=(ab)D=(0b)letP=(pq)equationswithα,β,γunknownatfirst(1)AP2=α2(2)BP2=β2(3)CP2=γ2(4)DP2=x2youcaneasilysolvethesystemforp,qandgetaformulaforx2.nowinsertallpossiblepermutationsof3,4,5forα,β,γ

Commented by mr W last updated on 18/May/22

you are right sir!  though there are infinitely many such  rectangles, but the distance to the  fourth vertex is constant.  x=(√(α^2 +β^2 −γ^2 ))  x=(√(3^2 +4^2 −5^2 ))=0  x=(√(3^2 +5^2 −4^2 ))=3(√2)  x=(√(4^2 +5^2 −3^2 ))=4(√2)

youarerightsir!thoughthereareinfinitelymanysuchrectangles,butthedistancetothefourthvertexisconstant.x=α2+β2γ2x=32+4252=0x=32+5242=32x=42+5232=42

Commented by mr W last updated on 18/May/22

Commented by mr W last updated on 18/May/22

α^2 =a_1 ^2 +b_2 ^2   β^2 =a_2 ^2 +b_1 ^2   ⇒α^2 +β^2 =a_1 ^2 +a_2 ^2 +b_1 ^2 +b_2 ^2   x^2 =a_2 ^2 +b_2 ^2   γ^2 =a_1 ^2 +b_1 ^2   ⇒x^2 +γ^2 =a_1 ^2 +a_2 ^2 +b_1 ^2 +b_2 ^2   ⇒x^2 +𝛄^2 =𝛂^2 +𝛃^2

α2=a12+b22β2=a22+b12α2+β2=a12+a22+b12+b22x2=a22+b22γ2=a12+b12x2+γ2=a12+a22+b12+b22x2+γ2=α2+β2

Commented by Tawa11 last updated on 08/Oct/22

Great sirs

Greatsirs

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