Answer:
x = 135°
Explanation:
The angle x is the same fraction of 360° that the shaded area is of the area of the circle.
The area of a circle is given by the formula ...
A = πr²
For a radius of 12 cm, the area of the circle is ...
A = π(12 cm)² = 144π cm²
Then the measure of angle x is ...
x = (54π cm²)/(144π cm²)×360°
x = 135°