Someone help me out plss

 C) 611 square miles

Step-by-step explanation:

Create a perpendicular from the vertex (A) to the base (BC) which creates a 30-60-90 triangle on the right side. Label this point D.

Use the 30-60-90 triangle rules (b - b√3 - 2b)  to calculate the height of the triangle.

2b = 47  --> b = 23.5

AD = b√3 = 23.5√3

Area of a triangle = (1/2) base x height

                             = (1/2)  30    x  23.5√3

                             = 610.5479

                             ≈ 611

since the airplane is moving with constant speed then the distance travelled can be calculated by x=u*t

in km/h would be:

x=640*3.5=2.240 km

in m/s would be:

u=640 km/h= 640.000 m/h =640.000/ 3600 m/s =177.8 m/s

t= 3.5 h= 3.5 * 3600 s=12.600 s

then x=u*t= 177.8*12.600= 2.240.280 m