SOLUTION: Three angles of an irregular octagon are 100,120,140degrees.The remaining angles are congruent.find the size of each of the remaining angles.

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Question 1108828: Three angles of an irregular octagon are 100,120,140degrees.The remaining angles are congruent.find the size of each of the remaining angles.
Answer by ikleyn(52832) About Me  (Show Source):
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100 + 120 + 140 + (8-3)*x = (8-2)*180   degrees.   <<<---=== Each side is the sum of interior angles of the octagon.


Simplify and solve for x:


360 + 5x = 6*180,

5x = 6*180 - 360 = 720  ====>  x = 720%2F5 = 144.


Answer.  144 degrees.

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The referred lessons are the part of this online textbook under the topic  "Finding angles of triangles, parallelograms and rectangles".


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