$1//$Lab$9-1.$cpp $$ circle calculations $2//$Created$/$revised by on $34$ #include $5$ #include $6$ using namespace std; $78//$function prototypes $9$ double getArea$($double rad$)$;$10$ double getDiameter$($double rad$)$;$1112$ int main$()13\{14$ int choice $=0$;$15$ double radius $=0\mathrm{.}0$;$1617$ cout $<<"1$ Circle area" $<<$ endl;$18$ cout $<<"2$ Circle diameter" $<<$ endl;$19$ cout $<<$ "Enter your choice $(1$ or $2)$: $"$;$20$ cin $>>$ choice;$2122$ if $($choice $<1||$ choice $>2)23$ cout $<<$ "Invalid choice" $<<$ endl;$24$ else$25\{26$ cout $<<$ "Radius: $"$;$27$ cin $>>$ radius;$28$ if $($choice $==1)29$ cout $<<$ "Area: $"<<$ getArea$($radius$)$;$30$ else$31$ cout $<<$ "Diameter: $"<<$ getDiameter$($radius$)$;$32//$end if$33$ cout $<<$ endl;$34\}//$end if$35$ return $0$;$36\}//$end of main function$3738//*****$function definitions$*****39$ double getArea$($double rad$)40\{41$ const double PI $=3\mathrm{.}141593$;$42$ double area $=0\mathrm{.}0$;$43$ area $=$ PI $*$ pow$($rad$,2)$;$44$ return area;$45\}//$end getArea function$4647$ double getDiameter$($double rad$)48\{49$ return $2*$ rad;$50\}//$end getDiameter functionFigure $9-26$ Code for Lab $9-1$QUeStIONS$1.$ Why are the statements on Lines $9$ and $10$ necessary?$2.$ How else could you write the statement on Line $9?3.$ If the program does not include the outer selection structure, what will the program display if the user enters the numbers $3$ and $10$ as the choice and radius, respectively?$4.$ What are the scope and lifetime of the choice and radius variables?$5.$ What are the scope and lifetime of the rad variable used in the getArea function? $6.$ What are the scope and lifetime of the PI constant and the area variable?$7.$ What scope and lifetime of the rad varible used in to get the diameter function?