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The-figure-below-represents-a-design-on-the-windows-of-a-building-The-curved-part-XY-is-an-arc-of-a-circle-The-rise-of-the-segmental-arc-is-10cm-its-span-is-100cm-and-XZ-ZY-120cm-calculate-i-th




Question Number 204873 by necx122 last updated on 29/Feb/24
The figure below represents a design  on the windows of a building. The  curved part XY is an arc of a circle.  The rise of the segmental arc is 10cm,  its span is 100cm and XZ=ZY=120cm.  calculate:  (i) the radius of the circle  (ii) the area of the segmental cap,  correct to 2 significant figures.  (iii) the total area of the design, correct  to 3 significant figures.
Thefigurebelowrepresentsadesignonthewindowsofabuilding.ThecurvedpartXYisanarcofacircle.Theriseofthesegmentalarcis10cm,itsspanis100cmandXZ=ZY=120cm.calculate:(i)theradiusofthecircle(ii)theareaofthesegmentalcap,correctto2significantfigures.(iii)thetotalareaofthedesign,correctto3significantfigures.
Commented by necx122 last updated on 29/Feb/24
Commented by necx122 last updated on 29/Feb/24
I will really need our help on this. Thanks in advance.
Answered by A5T last updated on 29/Feb/24
Construct the perpendicular bisector of XY,  then Z and O,centre of circle, lie on it.  R^2 =50^2 +(R−10)^2 ⇒R^2 =50^2 +R^2 −20R+100  ⇒20R=2600⇒R=130cm  100^2 =2×130^2 −2×130^2 cosXOY  ⇒cosXOY=((119)/(169))⇒sinXOY=((120)/(169))  ⇒Area of sector=((sin^(−1) (((120)/(169))))/(360))×130^2 π≈6671.9699  Area of XOY=65×130×((120)/(169))=6000  ⇒Area of segmental arc≈671.9699cm^2   ⇒Total area of design≈60×120×((5(√(119)))/(72))−671.9699  500(√(119))−671.9699≈4782.389  [100^2 =2×120^2 −2×120^2 cosXZY⇒cosXZY=((47)/(72))  ⇒sinXZY=((5(√(119)))/(72))]
ConstructtheperpendicularbisectorofXY,thenZandO,centreofcircle,lieonit.R2=502+(R10)2R2=502+R220R+10020R=2600R=130cm1002=2×13022×1302cosXOYcosXOY=119169sinXOY=120169Areaofsector=sin1(120169)360×1302π6671.9699AreaofXOY=65×130×120169=6000Areaofsegmentalarc671.9699cm2Totalareaofdesign60×120×511972671.9699500119671.96994782.389[1002=2×12022×1202cosXZYcosXZY=4772sinXZY=511972]
Commented by necx122 last updated on 29/Feb/24
This is clear, understandable and  precise. Thank you sir.
Thisisclear,understandableandprecise.Thankyousir.

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