java简单练习题及答案

1、 p1包，A类，3个方法sin(double a),cos(double a),tan double a (),分别返回相应的三角函数计算的值。

答案：

package p1;

public class A {

public double sin(double a)

{

return Math.sin(a);

}

public double cos(double a)

{

return Math.cos(a);

}

public double tan(double a) {

return Math.tan(a);

}

}

2、 P2包，B类，主方法测试上面的3个方法。

答案：

package p2;

import p1.A;

public class B {

} public static void main(String[] args) { } A a1=new A(); System.out.println(a1.sin(Math.PI/6)); System.out.println(a1.cos(Math.PI/3)); System.out.println(a1.tan(Math.PI/4));

运行结果：

0.49999999999999994

0.5000000000000001

0.9999999999999999

附加1、2题及直接写度数：

package p1;

public class A {

public double sin(double a)

{

return Math.sin(a*Math.PI/180);

}

public double cos(double a)

{

return Math.cos(a*Math.PI/180);

}

public double tan(double a)

{

return Math.tan(a*Math.PI/180);

}

public double cot(double a)

{

return 1/tan(a*Math.PI/180);//cot(a)=1/tan(a); }

public double sec(double a)

{

return 1/cos(a*Math.PI/180);//sec(a)=1/cos(a); }

public double csc(double a)

{

return 1/sin(a*Math.PI/180);//csc(a)=1/sin(a); }

}

package p2;

import p1.A;

public class B {

}

public static void main(String[] args) { } A a1=new A(); System.out.println(a1.sin(30)); System.out.println(a1.cos(30)); System.out.println(a1.tan(30)); System.out.println(a1.cot(30)); System.out.println(a1.sec(30)); System.out.println(a1.csc(30));

附加成方、正变负负变正：

package p1;

public class A {

private double s;//封装S public void setS(double s) { } public double getS() { } return this.s; this.s=s;

public double sq(double a)//开方

{

return Math.sqrt(a);

}

public double zf(double a)// 正变负负变正 {

return a*(-1);

}

}

package p2;

import p1.A;

public class B {

} public static void main(String[] args) { } A a1=new A(); System.out.println(a1.sq(30)); System.out.println(a1.zf(30));

3、p1包，A类方法rate（double a），返回应缴纳的个人所得税。

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