Question 471579
A supplementary angle is the angle that when added to a given angle makes the total 180 degrees.
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You are given an angle with a measure of 49 degrees. Its supplementary angle must have a measure that when added to 49 degrees gives a total measure of 180 degrees.
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In equation form this would be:
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49 + S = 180
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where S represents the measure of the supplementary angle.  To solve this equation subtract 49 degrees from both sides. This eliminates the 49 degrees from the left side and you have:
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S = 180 - 49
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Perform the subtraction on the right side and the result is:
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S = 131 degrees.
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So the measure of the supplementary angle for 49 degrees is 131 degrees which is the second entry on your list of possible answers.
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Hope this helps you to understand what a supplementary angle is and how it can be calculated.