Answer:
(a) 120° or 133.33 grades.
(b)135° or 150 grades.
(c) 144° or 160 grades.
(d) 150° or 166.67 grades.
(e) 154.29° or 171.43 grades.
(f) 157.5° or 175 grades.
(g) 160° or 177.78 grades.
(h) 162° or 180 grades.
Step-by-step explanation:
A regular polygon is a polygon that has all sides and all angles equal.
Each interior angle, k (measured in degrees), of a regular polygon is given by;
k = s ÷ n -----------(k)
Where;
s = sum of the interior angle of the polygon.
n = number of sides of the polygon
To get s, we use
s = (n - 2) x 180 [This is the formula to calculate the sum of the interior angles of a polygon]
Substituting s this into equation (i) gives
k = (n - 2) x 180 ÷ n
k = 180(n - 2) ÷ n -------------(ii)
(a) Triangle.
A triangle has n = 3 sides, therefore, each interior angle of a triangle is found by substituting n = 3 into equation (ii)
k = 180(3 - 1) ÷ 3
k = 180(2) ÷ 3
k = 180 x 2 ÷ 3
k = 360 ÷ 3
k = 120°
Convert to grade.
Remember that;
90° = 100 grades
∴ 120° = [tex]\frac{120 * 100}{90}[/tex] grades
⇒ 120° = 133.33 grades.
Therefore, each interior angles of a regular triangle is 120° or 133.33 grades.
(b) Quadrilateral.
A quadrilateral has n = 4 sides, therefore, each interior angle of a quadrilateral is found by substituting n = 4 into equation (ii)
k = 180(4 - 1) ÷ 4
k = 180(3) ÷ 4
k = 180 x 3 ÷ 4
k = 540 ÷ 4
k = 135°
Convert to grade.
Remember that;
90° = 100 grades
∴ 135° = [tex]\frac{135 * 100}{90}[/tex] grades
⇒ 135° = 150 grades.
Therefore, each interior angles of a regular quadrilateral is 135° or 150 grades.
(c) Pentagon
A pentagon has n = 5 sides, therefore, each interior angle of a pentagon is found by substituting n = 5 into equation (ii)
k = 180(5 - 1) ÷ 5
k = 180(4) ÷ 5
k = 180 x 4 ÷ 5
k = 720 ÷ 5
k = 144°
Convert to grade.
Remember that;
90° = 100 grades
∴ 144° = [tex]\frac{144 * 100}{90}[/tex] grades
⇒ 144° = 160 grades.
Therefore, each interior angles of a regular pentagon is 144° or 160 grades.
(d) Hexagon
A hexagon has n = 6 sides, therefore, each interior angle of a hexagon is found by substituting n = 6 into equation (ii)
k = 180(6 - 1) ÷ 6
k = 180(5) ÷ 6
k = 180 x 5 ÷ 6
k = 900 ÷ 6
k = 150°
Convert to grade.
Remember that;
90° = 100 grades
∴ 150° = [tex]\frac{150 * 100}{90}[/tex] grades
⇒ 150° = 166.67 grades.
Therefore, each interior angles of a regular hexagon is 150° or 166.67 grades.
(e) Heptagon
A heptagon has n = 7 sides, therefore, each interior angle of a heptagon is found by substituting n = 7 into equation (ii)
k = 180(7 - 1) ÷ 7
k = 180(6) ÷ 7
k = 180 x 6 ÷ 7
k = 1080 ÷ 7
k = 154.29°
Convert to grade.
Remember that;
90° = 100 grades
∴ 154.29° = [tex]\frac{154.29 * 100}{90}[/tex] grades
⇒ 154.29° = 171.43 grades.
Therefore, each interior angles of a regular heptagon is 154.29° or 171.43 grades.
(f) Octagon
An octagon has n = 8 sides, therefore, each interior angle of a octagon is found by substituting n = 8 into equation (ii)
k = 180(8 - 1) ÷ 8
k = 180(7) ÷ 8
k = 180 x 7 ÷ 8
k = 1260 ÷ 8
k = 157.5°
Convert to grade.
Remember that;
90° = 100 grades
∴ 157.5° = [tex]\frac{157.5 * 100}{90}[/tex] grades
⇒ 157.5° = 175 grades.
Therefore, each interior angles of a regular octagon is 157.5° or 175 grades.
(g) Nonagon
A nonagon has n = 9 sides, therefore, each interior angle of a nonagon is found by substituting n = 9 into equation (ii)
k = 180(9 - 1) ÷ 9
k = 180(8) ÷ 9
k = 180 x 8 ÷ 9
k = 1440 ÷ 9
k = 160°
Convert to grade.
Remember that;
90° = 100 grades
∴ 160° = [tex]\frac{160 * 100}{90}[/tex] grades
⇒ 160° = 177.78 grades.
Therefore, each interior angles of a regular nonagon is 160° or 177.78 grades.
(h) Decagon
A decagon has n = 10 sides, therefore, each interior angle of a decagon is found by substituting n = 10 into equation (ii)
k = 180(10 - 1) ÷ 10
k = 180(9) ÷ 10
k = 180 x 9 ÷ 10
k = 1620 ÷ 10
k = 162°
Convert to grade.
Remember that;
90° = 100 grades
∴ 162° = [tex]\frac{162 * 100}{90}[/tex] grades
⇒ 162° = 180 grades.
Therefore, each interior angles of a regular decagon is 162° or 180 grades.
