Each exterior angle of a regular decagon has a measure of [tex] (3x + 6)^\circ [/tex]. What is the value of [tex] x [/tex]?

A. [tex] x = 8 [/tex]
B. [tex] x = 10 [/tex]
C. [tex] x = 13 [/tex]
D. [tex] x = 18 [/tex]



Answer :

To find the value of [tex]\( x \)[/tex] when given that each exterior angle of a regular decagon (a 10-sided polygon) is [tex]\((3x + 6)^{\circ}\)[/tex], follow these steps:

1. Determine the measure of each exterior angle in a regular decagon:

A regular decagon has [tex]\( 10 \)[/tex] sides. The sum of all exterior angles of any polygon is always [tex]\( 360^{\circ} \)[/tex]. Therefore, each exterior angle of a regular decagon is given by:
[tex]\[ \text{Each exterior angle} = \frac{360^{\circ}}{10} = 36^{\circ} \][/tex]

2. Set up the equation:

We are given that each exterior angle has the measure [tex]\( (3x + 6)^{\circ} \)[/tex]. So we set up the equation:
[tex]\[ 3x + 6 = 36 \][/tex]

3. Solve for [tex]\( x \)[/tex]:

Subtract 6 from both sides of the equation:
[tex]\[ 3x = 30 \][/tex]

Divide both sides by 3:
[tex]\[ x = 10 \][/tex]

4. Verify the solution:

Substitute [tex]\( x = 10 \)[/tex] back into the expression for the angle to check:
[tex]\[ 3(10) + 6 = 30 + 6 = 36 \][/tex]
This matches our calculated measure for each exterior angle of the decagon.

Therefore, the value of [tex]\( x \)[/tex] is [tex]\( \boxed{10} \)[/tex].