The values for x are:
question 15 ⇒x=8
question 16⇒x=19
question 17⇒x=14
Here you should apply your knowledge about regular polygons. The question asks the values of x that is a variable for some interior angles. Then, you will find x from the sum of interior angles of each regular polygon.
Sum of Interior Angles of Regular Polygon
There is a formula that relates number of sides polygon with its sum of interior angles. See below.
S=(n-2)*180°
S=sum of interior angles of regular polygon.
n=number of sides of regular polygon.
First, you should find the value for the sum of interior angles. Here, the regular polygon has 4 sides. Then,
S=(n-2)*180°
S=(4-2)*180°
S=2*180°=360°
Note that only 3 interior angles are shown in the figure. Nonetheless, the question gives an external angle (71°). Thus, the internal angle will be: 180-71=109°. This is because the interior and exterior angles are supplementary.
Next step, sum of interior angles for finding x
[tex]10x+6+13x-2+109+8x-1=360\\ \\ 31x=360-112\\ \\ 31x=248\\ \\ x=\frac{248}{31} =8[/tex]
x=8
First, you should find the value for the sum of interior angles. Here, the regular polygon has 6 sides. Then,
S=(n-2)*180°
S=(6-2)*180°
S=4*180°=720°
Next step, sum of interior angles for finding x.
[tex]90+9x-19+7x+3+111+5x+8+128=720\\ \\ 21x=720-321\\ \\ 21x=399\\ \\ x=\frac{399}{21} =19[/tex]
x=19
First, you should find the value for the sum of interior angles. Here, the regular polygon has 5 sides. Then,
S=(n-2)*180°
S=(5-2)*180°
S=3*180°=540°
The image of the question shows the sides are congruent, consequently, the angles are equal.
Next step, sum of interior angles for finding x.
[tex]9x-18+9x-18+9x-18+9x-18+9x-18=540\\ \\ 45x=540+90\\ \\ 45x=630\\ \\ x=\frac{630}{45} =14[/tex]
x=14
Read more about sum of interior angles here:
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