if you get how to do this could you please help me on this question?

Answer:
Step-by-step explanation:
area of the sector = 144 π
the whole circle is πr²= 36²π = 1,296π
the whole circle has an angle of 360°
the area of the sector has the angle ∠FAN
∠FAN/360 = 144π/1,296π
∠FAN = 360 * 144π/ 1,296π
∠FAN = 40°