As we know, the exterior angle plus the interior angle adds up to 180°, so the missing angles moving clockwise from the top are: 180 – 71.4 = 108.6° 180 – 56.4 = 123.6° ...

The sum of interior angles in a quadrilateral is 360°. This fact and the properties of quadrilaterals can be used to calculate angles. Example. Find angle \(d\). \(d = 360 - 100 - 70 - 30 = 160 ...