Category:External Angle of Triangle equals Sum of other Internal Angles

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This category contains pages concerning External Angle of Triangle equals Sum of other Internal Angles:


The external angle of a triangle equals the sum of the other two internal angles.


In the words of Euclid:

In any triangle, if one of the sides be produced, the exterior angle is equal to the two interior and opposite angles, and the three interior angles of the triangle are equal to two right angles.

(The Elements: Book $\text{I}$: Proposition $32$)

Pages in category "External Angle of Triangle equals Sum of other Internal Angles"

The following 3 pages are in this category, out of 3 total.