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Question Number 193975 by mr W last updated on 24/Jun/23

Commented by mr W last updated on 25/Jun/23

find the area of the hatched square.

findtheareaofthehatchedsquare.

Answered by mr W last updated on 25/Jun/23

Commented by mr W last updated on 25/Jun/23

cos α=((7^2 +9^2 −((√2)s)^2 )/(2×7×9))  cos (β+γ)=((2^2 +6^2 −((√2)s)^2 )/(2×2×6))=−cos α  ⇒((2^2 +6^2 −((√2)s)^2 )/(2×2×6))=−((7^2 +9^2 −((√2)s)^2 )/(2×7×9))  ⇒s^2 =((136)/5)=area of square

cosα=72+92(2s)22×7×9cos(β+γ)=22+62(2s)22×2×6=cosα22+62(2s)22×2×6=72+92(2s)22×7×9s2=1365=areaofsquare

Answered by Subhi last updated on 25/Jun/23

put ef^� b = α ,  fb^� e = β  , each side of the square = l  fd = (√(l^2 +l^2 ))=(√2)l  Δfbd: BD^2  = 2l^2 +6^2 −12(√2)lcos(45+α)  2+13^2 +36Q^2 =11(18+36+2l^2 −12(√2)l.cos(45+α)                                                             (stewart′s theorem)  36Q^2 −22l^2 +132(√2)l.cos(45+α)=256 →(i)  ΔAEB: h^2  = Q^2 +13^2 −26Qcos(β)  11^2 +13^2 =2Q^2 +2h^2       (Apollonius theorem)  11^2 +13^2 =4Q^2 +2×13^2 −52Qcos(β) (1)  Δefb: cos(β) = ((Q^2 +6^2 −l^2 )/(12Q))  (2)  compute 1,2  108 = ((13)/3)l^2 −(1/3)Q^2   (ii)  compute (i),(ii)  468l^2 −11664−22l^2 +132(√2)l.cos(45+α) = 256  446l^2 +132(√2)l.cos(45+α) = 11920 → (iii)  ΔADF: cos(135−α) = ((7^2 +2l^2 −9^2 )/(14(√2) l))=−cos(45+α) (3)  compute (iii), (3)  446l^2 −132(√2).(((2l^2 −32)/(14(√2))))=11920  l^2 =((11920−((132(√2).32)/(14(√2))))/(446−((264)/(14))))=((136)/5)=area of the square

putefb^=α,fbe^=β,eachsideofthesquare=lfd=l2+l2=2lΔfbd:BD2=2l2+62122lcos(45+α)2+132+36Q2=11(18+36+2l2122l.cos(45+α)(stewartstheorem)36Q222l2+1322l.cos(45+α)=256(i)ΔAEB:h2=Q2+13226Qcos(β)112+132=2Q2+2h2(Apolloniustheorem)112+132=4Q2+2×13252Qcos(β)(1)Δefb:cos(β)=Q2+62l212Q(2)compute1,2108=133l213Q2(ii)compute(i),(ii)468l21166422l2+1322l.cos(45+α)=256446l2+1322l.cos(45+α)=11920(iii)ΔADF:cos(135α)=72+2l292142l=cos(45+α)(3)compute(iii),(3)446l21322.(2l232142)=11920l2=119201322.3214244626414=1365=areaofthesquare

Commented by Subhi last updated on 25/Jun/23

Commented by mr W last updated on 26/Jun/23

thanks!

thanks!

Commented by Subhi last updated on 26/Jun/23

You are welcome

Youarewelcome

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