JAMB - Mathematics (1981 - No. 39)
What is the size of an exterior angle of a regular pentagon?
36o
60o
72o
120o
360o
Explication
Pentagon is a polygon with 5 sides. Sum of interior angles of polygon (regular) = (2n - 4) x 90o
= 5
= (10 - 4) x 90o
= 540o
each interior angle = \(\frac{540}{5}\)
= 108o
= 180o let x represent ext. angle
x + 108o = 180v
x = 180o - 108o
= 72o
= 5
= (10 - 4) x 90o
= 540o
each interior angle = \(\frac{540}{5}\)
= 108o
= 180o let x represent ext. angle
x + 108o = 180v
x = 180o - 108o
= 72o