Asin Method

# Math.Asin Method

Silverlight

Returns the angle whose sine is the specified number.

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

## Syntax

```[SecuritySafeCriticalAttribute]
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, but less 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.

## Remarks

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.

## Examples

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>
class Example
{
private double m_longBase;
private double m_shortBase;
private double m_leftLeg;
private double m_rightLeg;

public Example(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));
}

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

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

{
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);
}

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

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

public static void Demo(System.Windows.Controls.TextBlock outputBlock)
{
Example trpz = new Example(20.0, 10.0, 8.0, 6.0);
outputBlock.Text += String.Format("The trapezoid's bases are 20.0 and 10.0, the trapezoid's legs are 8.0 and 6.0") + "\n";
double h = trpz.GetHeight();
outputBlock.Text += "Trapezoid height is: " + h.ToString() + "\n";
outputBlock.Text += "Trapezoid left base angle is: " + dxR.ToString() + " Radians" + "\n";
outputBlock.Text += "Trapezoid right base angle is: " + dyR.ToString() + " Radians" + "\n";
double dxD = trpz.GetLeftBaseDegreeAngle();
outputBlock.Text += "Trapezoid left base angle is: " + dxD.ToString() + " Degrees" + "\n";
double dyD = trpz.GetRightBaseDegreeAngle();
outputBlock.Text += "Trapezoid left base angle is: " + dyD.ToString() + " Degrees" + "\n";
}
}

```

## Version Information

#### Silverlight

Supported in: 5, 4, 3

#### Silverlight for Windows Phone

Supported in: Windows Phone OS 7.1, Windows Phone OS 7.0

#### XNA Framework

Supported in: Xbox 360, Windows Phone OS 7.0

## Platforms

For a list of the operating systems and browsers that are supported by Silverlight, see Supported Operating Systems and Browsers.