The diagonals of a parallelogram

This calculator computes the diagonals of a parallelogram and adjacent angles from side lengths and angles between sides.

It is done with the help of law of cosines

Check the picture. First, we use the law of cosines to find out d1, then we find the second angle of a parallelogram, which is , then we again use the law of cosines to find out d2. The remaining angles are found from the same law of cosines. After that, we find diagonal intersection angles using the fact that the sum of triangle angles is 180.

The polygon diagonals of a parallelogram

Side a

Side b

Angle

°

′

″

Calculation precision

Digits after the decimal point: 2

Calculate

Diagonal d1

 

Diagonal d2

 

Second parallelogram angle

 

Angle between d1 and d2

 

Angle between a and d1

 

Angle between b and d1

 

Angle between a and d2

 

Angle between b and d2

 

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