C# 0 The Complete Reference

PART II

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621

public static double Sqr t(double 

v

)

Returns the square root of 

v.

public static double Tan(double 

v

)

Returns the tangent of 

v.

public static double Tanh(double 

v

)

Returns the hyperbolic tangent of 

v.

public static double Truncate(double 

v

)

Returns the whole number por tion of 

v.

public static decimal Truncate(decimal 

v

)

Returns the whole number por tion of 

v.

T

ABLE

 21-1 

Methods Defi ned by 

Math

(continued)

Method

Meaning

Here is an example that uses 

Sqrt( )

 to help implement the Pythagorean theorem. It 

computes the length of the hypotenuse given the lengths of the two opposing sides of a 

right triangle.

// Implement the Pythagorean Theorem.

using System;

class Pythagorean {

  static void Main() {

    double s1;

    double s2;

    double hypot;

    string str;

    Console.WriteLine("Enter length of first side: ");

    str = Console.ReadLine();

    s1 = Double.Parse(str);

    Console.WriteLine("Enter length of second side: ");

    str = Console.ReadLine();

    s2 = Double.Parse(str);

    hypot = Math.Sqrt(s1*s1 + s2*s2);

    Console.WriteLine("Hypotenuse is " + hypot);

  }

}

Here is a sample run:

Enter length of first side: 3

Enter length of second side: 4

Hypotenuse is 5

Next is an example that uses the 

Pow( )

 method to compute the initial investment 

required to achieve a desired future value given the annual rate of return and the number 

of years. The formula to compute the initial investment is shown here:

InitialInvestment

 = 

FutureValue

 / (1 + 

InterestRate

)

Years

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622

 

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