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Question Number 181432 by mr W last updated on 25/Nov/22

Commented by mr W last updated on 25/Nov/22

find the area of circle.

findtheareaofcircle.

Commented by universe last updated on 25/Nov/22

Commented by universe last updated on 25/Nov/22

AE^2 +BE^2  = 4  CE^2 +ED^2  = 16  AE^2 +BE^2 +CE^2 +ED^2  = 20  4r^2  = 20 ⇒ r^2  = 5  area of cricle = πr^2  = 5π

AE2+BE2=4CE2+ED2=16AE2+BE2+CE2+ED2=204r2=20r2=5areaofcricle=πr2=5π

Commented by mr W last updated on 25/Nov/22

thanks sir!  please prove that  AE^2 +BE^2 +CE^2 +ED^2  = 4r^2 .  because it′s not obvious.    btw, please post your answer as  “answer”, not as “comment”!  thank you!

thankssir!pleaseprovethatAE2+BE2+CE2+ED2=4r2.becauseitsnotobvious.btw,pleasepostyouranswerasanswer,notascomment!thankyou!

Commented by universe last updated on 25/Nov/22

https://youtu.be/1EkoaQJyrfk

Answered by HeferH last updated on 25/Nov/22

Commented by HeferH last updated on 25/Nov/22

(((a + 2b)/2))^2  + (((2a + b)/2) − b)^2 = r^2    ((a^2  + 4b^2  + 4ab + (2a − b)^2 )/4) = r^2      ((a^2  + 4b^2  + 4ab + 4a^2  + b^2  − 4ab)/4) = r^2    a^2 + b^2  + 4(a^2  + b^2 ) = 4r^2    but a^2  + b^2  = 4 ⇒   4 + 4(4) = 4r^2    20 = 4r^2    5 = r^2    A = πr^2  = 5π u^2

(a+2b2)2+(2a+b2b)2=r2a2+4b2+4ab+(2ab)24=r2a2+4b2+4ab+4a2+b24ab4=r2a2+b2+4(a2+b2)=4r2buta2+b2=44+4(4)=4r220=4r25=r2A=πr2=5πu2

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