Question

ABCDEFGHI is a regular 9-sided polygon.

Answer 1

Answer:

angle BEF = 100 degrees

Step-by-step explanation:

For a regular 9-sided polygon (nonagon),

each exterior angle = 360/9=40 degrees

each interior angle = 180-40 = 140 degrees.

Referring to diagram, in the trapezoid (trapezium) BCDE, the base angles are 180-140 = 40 degrees.

Therefore angle DEB = 40 degrees

that leaves BEF = 140-40 = 100 degrees