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Math.Asin Method

Returns the angle whose sine is the specified number.

Namespace:  System
Assemblies:   mscorlib (in mscorlib.dll)
  System.Runtime.Extensions (in System.Runtime.Extensions.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, 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.

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 example 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> 
using System;

namespace MathClassCS
{
	class MathTrapezoidSample
	{
		private double m_longBase;
		private double m_shortBase;
		private double m_leftLeg;
		private 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));
		}

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

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

		public 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);
		}

		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);
		}

		static void Main(string[] args)
		{
			MathTrapezoidSample trpz = new 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: " + h.ToString());
			double dxR = trpz.GetLeftBaseRadianAngle();
			Console.WriteLine("Trapezoid left base angle is: " + dxR.ToString() + " Radians");
			double dyR = trpz.GetRightBaseRadianAngle();
			Console.WriteLine("Trapezoid right base angle is: " + dyR.ToString() + " Radians");
			double dxD = trpz.GetLeftBaseDegreeAngle();
			Console.WriteLine("Trapezoid left base angle is: " + dxD.ToString() + " Degrees");
			double dyD = trpz.GetRightBaseDegreeAngle();
			Console.WriteLine("Trapezoid left base angle is: " + dyD.ToString() + " Degrees");
		}
	}
}

.NET Framework

Supported in: 4.6, 4.5, 4, 3.5, 3.0, 2.0, 1.1

.NET Framework Client Profile

Supported in: 4, 3.5 SP1

XNA Framework

Supported in: 3.0, 2.0, 1.0

Portable Class Library

Supported in: Portable Class Library

Supported in: Windows Phone 8.1

Supported in: Windows Phone Silverlight 8.1

Supported in: Windows Phone Silverlight 8
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