import java.util.Scanner;

public class cjava {

public static void main(String[]args) {

 float a,b,c,x1,x2;

 Scanner con=new Scanner(System.in);

 System.out.println("输入a,b,c的值:");

 a=con.nextInt();

 b=con.nextInt();

 c=con.nextInt();

 x1=(float)((-b+Math.sqrt(b*b-4*a*c))/(2*a));

 x2=(float)((-b-Math.sqrt(b*b-4*a*c))/(2*a));

 System.out.println("x1*"+x1);

 System.out.println("x2*"+x2);

}

package bgio;

import java.util.Scanner;

import java.lang.*;

public class cjava {

public static void main(String[]args) {

float a,b,c,x1,x2;

double s,area;

Scanner g=new Scanner(System.in);

System.out.println("输入a,b,c的值");

a=g.nextInt();

b=g.nextInt();

c=g.nextInt();

if(a+b>c&&b+c>a&&a+c>b) {

    s=(a+b+c)/2;

    area=Math.sqrt(s*(s-a)*(s-b)*(s-c));

    System.out.println("area="+area);

}

else

    System.out.println("it is not a trilateral!");

}

}

package bgio;

import java.util.Scanner;

public class cjava {

public static void main(String[]args) {

char ch;

Scanner g=new Scanner(System.in);

System.out.println("请输入ch:");

String s;

s=g.next();

ch=s.charAt(0);

if(ch>='A'&&ch<='Z') {

    ch+=+32;

    System.out.println(ch);

}

else

    System.out.println(ch);

}

}