Question 173686This question is from textbook Geometry
: Can you explain how to find the measure of an exterior angle
This question is from textbook Geometry
Answer by gonzo(654)   (Show Source):
You can put this solution on YOUR website! if you know the measure of the interior angle, then the exterior angle is 180 - it.
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the exterior angle is supplementary to its corresponding interior angle.
that means that 180 degrees - interior angle degrees = exterior angle degrees.
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if your interior angle is BAC (vertex at A), then take one of the sides (either BA or AC) and extend it past the vertex in a straight line to point D.
if you used line BA, it would be the extended line BD.
if you used line CA, it would be the extended line CD.
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you only use one, not both.
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you have now formed a new angle.
let's say you extended BA
your new line goes from B straight through A to D.
your new angle is BAD.
that angle is supplementary to BAC since the sum of BAC and BAD is 180 degrees.
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the exterior angle is always supplmentary to it's corresponding interior angle.
the exterior angle is always 180 degrees - the interior angle degrees.
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