This quadrilateral calculator helps you determine the area, perimeter, and angles of various types of quadrilaterals simply by entering the required dimensions.

## Quadrilateral Calculator

This Quadrilateral Calculator helps you calculate the area of a quadrilateral given the lengths of all four sides and one specified angle between two consecutive sides.

### How to Use the Calculator

- Enter the length of side A in the “Side A” field.
- Enter the length of side B in the “Side B” field.
- Enter the length of side C in the “Side C” field.
- Enter the length of side D in the “Side D” field.
- Enter the measure of the angle in degrees in the “Angle” field.
- Click the “Calculate” button to obtain the result.

### How It Calculates the Results

The calculator uses Bretschneider’s formula to calculate the area of a general quadrilateral, which is given by:

*Area = √((s-a)(s-b)(s-c)(s-d) – abcd (cos(θ/2))^2)*

where ‘*s*‘ is the semiperimeter of the quadrilateral, ‘*a*‘, ‘*b*‘, ‘*c*‘, ‘*d*‘ are the lengths of the sides, and ‘*θ*‘ is the angle between sides ‘*b*‘ and ‘*c*‘.

### Limitations

- The calculator assumes the input describes a valid quadrilateral. Providing the lengths of the sides that cannot form a quadrilateral will result in an incorrect area or an error message.
- The provided angle should be between two of the sides, otherwise the calculation may not represent the actual shape.
- The calculator does not check for convexity or concavity of the quadrilateral, and it assumes that the input forms a convex quadrilateral.