The measure of ∠FDE = 18°
Explanation:
A Pentagon has 5 sides and is made of 3 triangles
So, sum of the interior angles of the triangle = 180°
Therefore, the total interior angle of a regular pentagon = 3 X 180° = 540°
A regular pentagon will have all its angle equal
All the five angles would make 540°
Let the measure of one angle = x
So,
5x = 540°
x = 108°
Therefore, the measure of each angle of a pentagon is 108°
From the diagram,
∠AED + ∠FED = 180°
∠AED = 108° as it is one of the sides of the pentagon
So,
108° + ∠FED = 180°
∠FED = 72°
In ΔEFD,
∠FED + ∠EFD + ∠FDE = 180°
72° + 90° + ∠FDE = 180°
∠FDE = 18°
Therefore, the measure of ∠FDE = 18°
