The measure of arc EC is 50. Exterior angle theorem is used in the given problem.
What is the sum of a regular polygon's outer angles?
The sum of the exterior angles of a regular polygon with any number of sides equals 360°.
The exterior angle of a polygon is the angle of rotation between one extended side and its neighboring side, which is not extended.
Furthermore, because the polygon is regular, even though it has 'n' sides, all the outside angles have the same measure, and hence their measure is (360/n)°.
The measure of arc EC is found as;
[tex]\rm 7x = (90+5x)\times \frac{1}{2}\\\\ 7x=2.5x+45\\\\ 4.5 x=45 \\\\ x=10[/tex]
From the diagram,he EC is 5x . The measure of arc EC is;
EC=5x
EC=5×10
EC=50
Hence,the measure of arc EC will be 50.
Learn more about interior and exterior angles refer:
https://brainly.com/question/14173422
#SPJ2