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Math::Asin Method

Returns the angle whose sine is the specified number.

Namespace:  System
Assembly:  mscorlib (in mscorlib.dll)

public:
static double Asin(
	double d
)

Parameters

d
Type: System::Double

A number representing a sine, where d must be greater than or equal to -1.

Return Value

Type: System::Double
An angle, θ, measured in radians, such that -π/2 θ π/2
-or-
NaN if d < -1 or d > 1 or d equals NaN.

A positive return value represents a counterclockwise angle from the x-axis; a negative return value represents a clockwise angle.

Multiply the return value by 180/Math::PI to convert from radians to degrees.

The following code sample uses Asin to assist in the computation of the inner angles of a given trapezoid.

/// <summary> 
/// The following class represents simple functionality of the trapezoid. 
/// </summary> 
public ref class MathTrapezoidSample
{
private:
   double m_longBase;
   double m_shortBase;
   double m_leftLeg;
   double m_rightLeg;

public:
   MathTrapezoidSample( double longbase, double shortbase, double leftLeg, double rightLeg )
   {
      m_longBase = Math::Abs( longbase );
      m_shortBase = Math::Abs( shortbase );
      m_leftLeg = Math::Abs( leftLeg );
      m_rightLeg = Math::Abs( rightLeg );
   }


private:
   double GetRightSmallBase()
   {
      return (Math::Pow( m_rightLeg, 2.0 ) - Math::Pow( m_leftLeg, 2.0 ) + Math::Pow( m_longBase, 2.0 ) + Math::Pow( m_shortBase, 2.0 ) - 2 * m_shortBase * m_longBase) / (2 * (m_longBase - m_shortBase));
   }


public:
   double GetHeight()
   {
      double x = GetRightSmallBase();
      return Math::Sqrt( Math::Pow( m_rightLeg, 2.0 ) - Math::Pow( x, 2.0 ) );
   }

   double GetSquare()
   {
      return GetHeight() * m_longBase / 2.0;
   }

   double GetLeftBaseRadianAngle()
   {
      double sinX = GetHeight() / m_leftLeg;
      return Math::Round( Math::Asin( sinX ), 2 );
   }

   double GetRightBaseRadianAngle()
   {
      double x = GetRightSmallBase();
      double cosX = (Math::Pow( m_rightLeg, 2.0 ) + Math::Pow( x, 2.0 ) - Math::Pow( GetHeight(), 2.0 )) / (2 * x * m_rightLeg);
      return Math::Round( Math::Acos( cosX ), 2 );
   }

   double GetLeftBaseDegreeAngle()
   {
      double x = GetLeftBaseRadianAngle() * 180 / Math::PI;
      return Math::Round( x, 2 );
   }

   double GetRightBaseDegreeAngle()
   {
      double x = GetRightBaseRadianAngle() * 180 / Math::PI;
      return Math::Round( x, 2 );
   }

};

int main()
{
   MathTrapezoidSample^ trpz = gcnew MathTrapezoidSample( 20.0,10.0,8.0,6.0 );
   Console::WriteLine( "The trapezoid's bases are 20.0 and 10.0, the trapezoid's legs are 8.0 and 6.0" );
   double h = trpz->GetHeight();
   Console::WriteLine( "Trapezoid height is: {0}", h.ToString() );
   double dxR = trpz->GetLeftBaseRadianAngle();
   Console::WriteLine( "Trapezoid left base angle is: {0} Radians", dxR.ToString() );
   double dyR = trpz->GetRightBaseRadianAngle();
   Console::WriteLine( "Trapezoid right base angle is: {0} Radians", dyR.ToString() );
   double dxD = trpz->GetLeftBaseDegreeAngle();
   Console::WriteLine( "Trapezoid left base angle is: {0} Degrees", dxD.ToString() );
   double dyD = trpz->GetRightBaseDegreeAngle();
   Console::WriteLine( "Trapezoid left base angle is: {0} Degrees", dyD.ToString() );
}

Windows 7, Windows Vista, Windows XP SP2, Windows XP Media Center Edition, Windows XP Professional x64 Edition, Windows XP Starter Edition, Windows Server 2008 R2, Windows Server 2008, Windows Server 2003, Windows Server 2000 SP4, Windows Millennium Edition, Windows 98, Windows CE, Windows Mobile for Smartphone, Windows Mobile for Pocket PC, Xbox 360, Zune

The .NET Framework and .NET Compact Framework do not support all versions of every platform. For a list of the supported versions, see .NET Framework System Requirements.

.NET Framework

Supported in: 3.5, 3.0, 2.0, 1.1, 1.0

.NET Compact Framework

Supported in: 3.5, 2.0, 1.0

XNA Framework

Supported in: 3.0, 2.0, 1.0

Date

History

Reason

Updated return value information.

Customer feedback.

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