SOLUTION: Four of the interior angle of a pentagon are 80-y°, 80+y°,120-y°,120+y°. The size of the 5th interior angle must be???

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Question 1107197: Four of the interior angle of a pentagon are 80-y°, 80+y°,120-y°,120+y°. The size of the 5th interior angle must be???
Found 3 solutions by stanbon, ikleyn, TeachMath:
Answer by stanbon(75887)   (Show Source): You can put this solution on YOUR website!
Four of the interior angle of a pentagon are 80-y°, 80+y°,120-y°,120+y°. The size of the 5th interior angle must be???
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The sum of the interior angles of a pentagon are (5-1)*180 = 720 degrees
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Equation::
80-y + 80+y + 120-y + 120+y + 5th = 720
200+200 + 5th = 720
5th = 320 degrees
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Cheers,
Stan H.
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Answer by ikleyn(52914)   (Show Source): You can put this solution on YOUR website!
.
Four of the interior angle of a pentagon are 80-y°, 80+y°,120-y°,120+y°. The size of the 5th interior angle must be???
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The sum of the interior angles of a pentagon is (5-2)*180 = 540 degrees

Equation::

80-y + 80+y + 120-y + 120+y + 5th = 540

200+200 + 5th = 540

5th = 140 degrees

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Any other answer is incorrect.



Answer by TeachMath(96)   (Show Source): You can put this solution on YOUR website!

the interior angles of a pentagon (5-sided polygon) add up to 540 degrees, not 720 degrees.
that person (stanbon) is wrong, and the correct answer is 140 degrees.
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