Answer:
≈ 565.5 units²
Step-by-step explanation:
The area (A) of the shaded sector = area of circle × fraction of circle
A = πr² ×
← r is the radius
= π × 20² × 
= 400π × 0.45 ≈ 565.5 units²
I took five years before and it was hard for me to remember the postualates. I found it helpful to practice proving problems that involved the postualate. Some postualates like SAS are just abbreviations. SAS- Side-Angle-Side
Starting point: (0, 2) and can go to (1, 6).
This shows the slope and y-intercept. Hope this helps.
I am old, so I like to use paper & pencil