McGraw Hill Integrated II, 2012
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McGraw Hill Integrated II, 2012 View details
Mid-Chapter Quiz
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Exercise 6 Page 504

Use the Polygon Angle-Sum Theorem. How many sides does the polygon have?

Let's find the value of each interior angle.

We will start by finding the value of x. Recall the Polygon Angle-Sum Theorem.

Polygon Angle-Sum Theorem

The sum of the measures of the interior angles of a regular n -gon is given by:
(n-2)* 180^(∘)

In this case, expressions are given for the measures of the interior angles. We can write an equation where the sum of these expressions is equal to (n-2)180. x + (4x - 26) + x + (2x + 18) = (n - 2) * 180 Our polygon has 4 sides, so we substitute 4 for n and solve our equation for x.
x+(2x-16)+2x+(x+10)=(n-2)* 180
Solve for x

x+(2x-16)+2x+(x+10)=({\color{#0000FF}{4}}-2)\cdot 180

'"`UNIQ--MLMath-3-QINU`"'
x+(2x-16)+2x+(x+10)=2* 180
x+(2x-16)+2x+(x+10)=360
x+2x-16+2x+x+10=720-360
6x-6=360
6x=366
x=61
Now that we know the value of x, we can find the measures of the interior angles.
Measure of Interior Angle x=61 Simplified
x 61 61
2x-16 2( 61)-16 106
2x 2( 61) 122
x+10 ( 61)+10 71

Let's add these measures to our diagram.