From sin(180-x) = sin(x)
sin(150) = sin(180-30) = sin(30)
sin(120) = sin(180-60) = sin(60)
from cos(360-x) = cos(x)
cos(300) = cos(360-60) = cos(60)
cos(210) = cos(360-150) = cos(150)
from cos(180-x) = -cos(x)
cos(210) = cos(150) = cos(180-30) = -cos(30)
<h3>
Answer: a = 100</h3>
=============================================================
Explanation:
There are n = 7 sides to this polygon (so it's a heptagon)
The interior angles add up to 180(n-2) = 180*(7-2) = 900 degrees.
So that means,
69+284+62+62+242+81+a = 900
800+a = 900
a = 900-800
a = 100
