Question

2. Suppose the measures of the interior angles of a convex octagon are eight

numbers, each separated by a value of 1 degree from its neighbors. Find
the measure of the second smallest angle.
118°
131°
132.5°
142°
None of these answers are correct.

Answer 1

Answer: 132.5 degrees (choice C)

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Step-by-step explanation:

The interior angles are consecutive numbers such as 1,2,3,... or 7,8,9... and so on. The gap between any two adjacent neighbors is 1.

For any polygon with n sides, the interior angles add up to 180(n-2)

We have n = 8 sides so the interior angles sum to 180(n-2) = 180(8-2) = 1080 degrees.

Any octagon has its interior angles add up to 1080 degrees.

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Let x be the smallest angle. The next angle up is x+1. After that is x+2 and so on until we reach x+7 as the 8th angle.

Add up those 8 angles, set the sum equal to 1080 and solve for x

x+(x+1)+(x+2)+(x+3)+(x+4)+(x+5)+(x+6)+(x+7) = 1080

8x+28 = 1080

8x = 1080-28

8x = 1052

x = 1052/8

x = 131.5

This is the smallest angle. The next angle up or the second smallest angle is x+1 = 131.5+1 = 132.5 degrees (choice C)