The picture above shows a square, an equilateral triangle and a regular pentagon. Find the blue angle in degrees.
There are 360o around each point.
There are 60o in each vertex angle of an equilateral triangle.
There are 90o in each vertex angle of a square.
To find the number of degrees in each vertex angle of a regular pentagon, use this formula:
degrees = (n - 2)·180o / n (where n = number of sides) = (5 - 2)·180o / 5 = 108o.
360o - 60o - 90o - 108o = .....