The cross-section of a tunnel is a square of side 7 m surmounted by a semicircle as shown in the following figure.The tunnel is 80 m long. Calculate:(iii) its floor area contexto.140 3 years ago FIGURE: Side of square (a) = 7m the radius of semi-circle = 7/2 m Length of the tunnel = 80 m
![\[\begin{array}{*{35}{l}} Area\text{ }of\text{ }cross\text{ }section\text{ }of\text{ }the\text{ }front\text{ }part\text{ }=\text{ }{{a}^{2}}~+\text{ }{\scriptscriptstyle 1\!/\!{ }_2}\text{ }\pi {{r}^{2}} \\ =\text{ }7\text{ }x\text{ }7\text{ }+\text{ }{\scriptscriptstyle 1\!/\!{ }_2}\text{ }x\text{ }22/7\text{ }x\text{ }7/2\text{ }x\text{ }7/2 \\ =\text{ }49\text{ }+\text{ }77/4\text{ }{{m}^{2}} \\ =\text{ }\left( 196\text{ }+\text{ }77 \right)/\text{ }4 \\ =\text{ }273/4\text{ }{{m}^{2}} \\ \end{array}\]](https://www.learnatnoon.com/s/wp-content/ql-cache/quicklatex.com-73552d83b416c639c9bbb0d333e37083_l3.png "Rendered by QuickLaTeX.com")
![\[\left( iii \right)\text{ }Area\text{ }of\text{ }floor\text{ }=\text{ }l\text{ }x\text{ }b\text{ }=\text{ }7\text{ }x\text{ }80\text{ }=\text{ }560\text{ }{{m}^{2}}\]](https://www.learnatnoon.com/s/wp-content/ql-cache/quicklatex.com-f77dd7b6536ba28974aa0f546aa42c53_l3.png "Rendered by QuickLaTeX.com")
