class Trangle{?double sideA,sideB,sideC,area,length;?boolean boo;?public Trangle(double a,double b,double c)?{ ?????this.sideA=a;???????? this.sideB=b;???????? this.sideC=c;?? ?if(this.sideA+this.sideB>this.sideC&&this.sideA+this.sideC>this.sideB&&this.sideB+this.sideC>this.sideA)?{??this.boo=true;???}?else?{??this.boo=false;???}?return boo;?}public?double getLength(){??if(this.sideA+this.sideB>this.sideC&&this.sideA+this.sideC>this.sideB&&this.sideB+this.sideC>this.sideA)??{???double p=(sideA+sideB+sideC)/2.0;???area=Math.sqrt(p*(p-sideA)*(p-sideB)*(p-sideC));???return area;?????}??else??{???System.out.println("不是一個三角形，不能計算面積");???return 0;??}???}public void setABC(double a,double b,double c){?this.sideA=a;??? this.sideB=b;??? this.sideC=c;??? if(this.sideA+this.sideB>this.sideC&&this.sideA+this.sideC>this.sideB&&this.sideB+this.sideC>this.sideA)??? {???? ?this.boo=true;??? }??? else??? {??? ?this.boo=false;??? }? ? }}class Lader{?double above,bottom,height,area;?Lader(double a,double b,double h)?{??this.above=a;??this.bottom=b;??this.height=h;???}public?double getArea(){??this.area=(this.above+this.bottom)*this.height/2;??return this.area;?}?}?public class AreaAndLength {?public static void main(String[] args)?{double length,area;Trangle trangle=null;Lader lader;trangle=new Trangle();lader=new Lader();length=trangle.getLength();System.out.println("三角形的周長："+length);area=trangle.getArea();System.out.println("三角形的面積："+area);area=lader.getArea();System.out.println("梯形的面積："+area);trangle.setABC(12,34,1);area=trangle.getArea();System.out.println("三角形的面積："+area);length=trangle.getLength();System.out.println("三角形的周長："+length);}}class Trangle{?double sideA,sideB,sideC,area,length;?boolean boo;?public Trangle(double a,double b,double c)?{ ?????this.sideA=a;???????? this.sideB=b;???????? this.sideC=c;?? ?if(this.sideA+this.sideB>this.sideC&&this.sideA+this.sideC>this.sideB&&this.sideB+this.sideC>this.sideA)?{??this.boo=true;???}?else?{??this.boo=false;???}?return boo;?}public?double getLength(){??if(this.sideA+this.sideB>this.sideC&&this.sideA+this.sideC>this.sideB&&this.sideB+this.sideC>this.sideA)??{???double p=(sideA+sideB+sideC)/2.0;???area=Math.sqrt(p*(p-sideA)*(p-sideB)*(p-sideC));???return area;?????}??else??{???System.out.println("不是一個三角形，不能計算面積");???return 0;??}???}public void setABC(double a,double b,double c){?this.sideA=a;??? this.sideB=b;??? this.sideC=c;??? if(this.sideA+this.sideB>this.sideC&&this.sideA+this.sideC>this.sideB&&this.sideB+this.sideC>this.sideA)??? {???? ?this.boo=true;??? }??? else??? {??? ?this.boo=false;??? }? ? }}class Lader{?double above,bottom,height,area;?Lader(double a,double b,double h)?{??this.above=a;??this.bottom=b;??this.height=h;???}public?double getArea(){??this.area=(this.above+this.bottom)*this.height/2;??return this.area;?}?}?public class AreaAndLength {?public static void main(String[] args)?{double length,area;Trangle trangle=null;Lader lader;trangle=new Trangle();lader=new Lader();length=trangle.getLength();System.out.println("三角形的周長："+length);area=trangle.getArea();System.out.println("三角形的面積："+area);area=lader.getArea();System.out.println("梯形的面積："+area);trangle.setABC(12,34,1);area=trangle.getArea();System.out.println("三角形的面積："+area);length=trangle.getLength();System.out.println("三角形的周長："+length);}}