Find the area of the shaded region.

Answer:
18π cm² ≈ 56.5 cm²
Step-by-step explanation:
The area of the sector can be found using an appropriate area formula.
When the sector central angle is given in radians, the formula for the area of that sector is ...
A = 1/2r²θ . . . . . . where θ is the central angle, and r is the radius
When the angle is in degrees, the formula will include a factor to convert it to radians:
A = 1/2r²θ(π/180) . . . . where angle θ is in degrees
A = (πθ/360)r² . . . . simplified slightly
The figure shows r=9 cm, and θ=80°. Using these values in the formula gives an area of ...
A = π(80/360)(9 cm)² = 18π cm² ≈ 56.5 cm²