已知函数double area(double x)用于求半径为x的圆面积 主函数调用该函数求圆面积 补充完整程序double area(double x ){double a;a=3.14*x*x;________________;}void main(){double a=5;printf("%lf",_____________________);}

已知函数double area(double x)用于求半径为x的圆面积 主函数调用该函数求圆面积 补充完整程序double area(double x ){double a;a=3.14*x*x;________________;}void main(){double a=5;printf(%lf,_____________________);} 编写函数double rect-area(double length,double width=0),编写函数double rect-area(double length,double width=0)：当width=0时计算正方形面积,否则计算长方形面积 #includeusing namespace std;#define PI 314159double area(double radius=0);double area(double a,double b);double area(double a,double b,double h);double area(double a,double b,double c,int);int main(){cout varible is being used without being initialized#include#includedouble main(void){double a,b,c,d,x1,x2;printf(enter a: );scanf(%lf,&a);printf(enter b: );scanf(%lf,&b);printf(enter c: );scanf(%lf,&c);d=b*b-4*a*c;if(d>0){void 函数1(doub 编程中各种符号的意思麻烦解释一下#include double x = 1.0,y = 2.0;double add( double x,double y ) {double sum;sum = x + y;}double average( double x,double y ) {double result;result = add( x,y ) / 2.0;return result;}int main( void) {doub 编一个类,有个方法double area (double a double b double c);求面积用海伦公式,再编个主类来调用该方法 用java写一个函数area,接收一个double类型的参数（表示圆的半径r）,用于计算圆的面积然后调用该函数计算半径为3的圆的面积 函数声明：double gauss_ch2(double(*f)(double),int n) 这里的double(*f)(double)是什么意思?传入什么? 以下函数定义中正确的是 （）以下函数定义中正确的是 （） .A.double fun(double x,double y){ } B.double fun(double x;double y){ }C.double fun(double x,double y);{ } D.double fun(double x,y){ }A.double fun(double x,double y){ } B 求助.圆类Circle继承自抽象基类Shape,圆的内接正方形类InnerSquare和外切正方形类OuterSquare都继承自圆类；分别实现求取圆、圆的内接正方形和外切正方形的面积和周长的函数double area()和double per double double double double double double double double