Big Ideas Math Geometry, 2014
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Big Ideas Math Geometry, 2014 View details
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Exercise 1 Page 385

Recall how many sides we had to add in the mentioned exercise. Then, look for a relation between this number and 540^(∘).

540 = 3* 180^(∘)

Practice makes perfect

In the mentioned exercise, we were given a convex polygon and were asked to find the number of sides we would have to add to the polygon to increase the sum of the interior angle measures by 540^(∘). To find the answer, we used the Polygon Interior Angles Theorem, which gives us a formula for the sum of the interior angle measures of a convex polygon with n sides. (n-2)180^(∘) Using this formula, we wrote an equation and solved it to find that we would have to add 3 sides to the polygon to increase the sum of the interior angle measures by 540^(∘). Now we are asked to find the relationship between the 540^(∘) increase and the answer. To do so, let's say we have a polygon with x sides. We can find the sum of the interior angle measures using the formula. ( x-2)180^(∘) Let's see what happens to the sum of the interior angle measures when we increase the number of sides by 1. To do so, we substitute x + 1 for x in our expression.

(x-2)180^(∘)
( x+1 -2)180^(∘)
(1 + x - 2)180^(∘)
1* 180^(∘) + (x-2)180^(∘)
180^(∘) + (x-2)180^(∘)

Increasing the number of sides of a convex polygon by 1 increases the sum of the interior angle measures by 180^(∘). Since 540^(∘) is 3 times 180^(∘), we again see that we have to add 3 sides to the polygon to increase the sum of the interior angle measures by 540^(∘). It also allows us to write a relation between the answer 3 and the 540^(∘) increase. 540^(∘) = 3* 180^(∘)