Angle facts

Sum

Sum of angles Sum of angles connected to a line from the one side = 180 degrees.

Sum of angles in triangle Sum of angles in any triangle = 180 degrees.

Sum of angles in right triangle Sum of the two smaller angles in a right-angled triangle = 90 degrees.

Equality

Cross angles When a line crosses parallel lines alternate angles are equal and corresponding angles are equal.
When two lines cross, opposite angles are equal.

Cross angles If in a triangle all sides equal, the angles are all 60 degrees.

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