1.?編寫程序計算半徑為5的圓的周長，計算公式為：周長=2*半徑*圓周率。

package?suannaigongyuan;

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import?java.util.Scanner;

import?static??java.lang.System.out;

import?java.util.Date;

import?java.util.Arrays;

import?java.util.Scanner;

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import?java.util.TreeSet;

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public?class?q3095563063 {

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public?static?void?main(String[] args) {

double?radius=5.0;

double?length;

final?double?pi=3.14;

length=2*radius*pi;

System.out.println("長是:"+length);

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}

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}