Measure of each interior angle of the regular pentagon =
(5−2)×180°
5
=
540°
5
=108° ∠BCJ = ∠CBF = 108° ∴ ∠ACB = ∠ABC =180°−108°=72° Using angle sum property in ABC,we have ∠A=180°−(∠ACB+∠ABC) =180°−(72°+72°) =180°−144=36° Thus, the measure of each angle at the angular points of the star figure is 36°. Formula :Each interior angle of the regular polygon of side n=