`"AA" = 2 * tan^-1( sqrt(((s- "b" )(s- "c" ))/(s*(s- "a" )))) _(where) "s" = ( "a" + "b" + "c" )/2`

Enter a value for all fields

The Triangle Angle calculator computes the interior angle (AA) of a triangle given the length of the three sides (a, b & c).

INSTRUCTIONS: Choose units and enter the following:

• (a) the length of side a
• (b) the length of side b
• (c) the length of side c

Triangle Angle (AA): The calculator returns the angle in degrees.  However, this can be automatically converted to other angle units (e.g. radians) via the pull-down menu.

The Math/Science

This is derived from the following equation:

`tan("AA"/2) = sqrt( ((s-b)(s-c)) / (s*(s-a)) )`     where the semi-perimeter: `s = (a + b + c)/2`

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Triangle Calculators

• Area of a triangle base on the base and height
• Area of a triangle using two sides and the interior angle.
• Area of a triangle using two angles and the interior side.
• Area of a triangle using three known sides.
• Area of Equilateral Triangle
• Area of a triangle defined by three points (x,y) in a plane.
• Height of a triangle based on the area and base
• Interior Angle of a triangle based on the length of three sides
• Semi-perimeter of a triangle
• Area between two vectors
• Compute the Distance Between a Point and a Line
• Compute the area of a triangle defined by three points
• Compute the distance between two points
• Compute the slope intercept form of a line from two points
• Compute the mid-point between two points

References

• Light and Matter(Dr. Benjamin Crowell) Chapter 0.12 Summary