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Question Number 182006 by mr W last updated on 03/Dec/22

Commented by mr W last updated on 03/Dec/22

find the largest area of an inscribed  right−angle triangle in a given acute  triangle with sides a,b,c. (a≥b≥c)

findthelargestareaofaninscribedrightangletriangleinagivenacutetrianglewithsidesa,b,c.(abc)

Commented by Acem last updated on 03/Dec/22

Interesting one!

Interestingone!

Answered by mr W last updated on 03/Dec/22

Commented by mr W last updated on 03/Dec/22

A_(max) =((a^2  sin γ cos γ)/2)=((a^2  sin 2γ)/4)

Amax=a2sinγcosγ2=a2sin2γ4

Commented by Acem last updated on 03/Dec/22

The 2nd one_(below) = ((a^2  sin β cos β)/2)= ((a^2  sin 2β)/4)   β> γ then the 2nd triangle is larger than the 1st

The2ndonebelow=a2sinβcosβ2=a2sin2β4β>γthenthe2ndtriangleislargerthanthe1st

Commented by mr W last updated on 03/Dec/22

don′t you see that β>γ doesn′t   automatically mean that the second   triangle is larger than the first one?   look at the diagram below.

dontyouseethatβ>γdoesntautomaticallymeanthatthesecondtriangleislargerthanthefirstone?lookatthediagrambelow.

Commented by mr W last updated on 03/Dec/22

Commented by mr W last updated on 03/Dec/22

Commented by mr W last updated on 03/Dec/22

this picture shows that the first  triangle (=((a^2  sin 2γ)/4)) is always larger  than the second one (=((a^2 sin 2β)/4)).

thispictureshowsthatthefirsttriangle(=a2sin2γ4)isalwayslargerthanthesecondone(=a2sin2β4).

Commented by Acem last updated on 03/Dec/22

Commented by Acem last updated on 03/Dec/22

We may say here that △MAC > BAN   It′s ok But, Area_(MAC)  = (1/2) b ∣AM∣= (1/2) b^( 2)  tan γ   So how can we judge? cause all your posts made   me think that the maximum area is when the   right angle be on the 2nd side “middle length” &   the hypotenuse is whole of the side “a” with   a formula ((a^2  sin 2γ)/4)  ∣^( ?)  (1/2) b^( 2)  tan γ    Note: I thought through diagram 1 that you say   that there′s 2 triangles as maximum

WemaysayherethatMAC>BANItsokBut,AreaMAC=12bAM∣=12b2tanγSohowcanwejudge?causeallyourpostsmademethinkthatthemaximumareaiswhentherightanglebeonthe2ndsidemiddlelength&thehypotenuseiswholeofthesideawithaformulaa2sin2γ4?12b2tanγNote:Ithoughtthroughdiagram1thatyousaythattheres2trianglesasmaximum

Commented by Acem last updated on 04/Dec/22

I back to your question, you mentioned that it is   an acute triangle, well can now say? :   For  a≥ b ≥ c   then:   maximum  { ((in an cute tri.      ((a^2  sin 2γ)/4))),((in obtuse tri.       ((b^2  tan γ)/2)  _(You agree?) )) :}

Ibacktoyourquestion,youmentionedthatitisanacutetriangle,wellcannowsay?:Forabcthen:maximum{inancutetri.a2sin2γ4inobtusetri.b2tanγ2Youagree?

Commented by mr W last updated on 04/Dec/22

agree.

agree.

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