If the area of an equilateral triangle is 9√3 sq ft, how long is a side? 6 ft. 9 ft. 18 ft.

Recalling that the area of a triangle of base b and height h is (1/2)(base)(height),

we equate this formula to the given area, 9√3, of this equilateral triangle:

(1/2)(base)(height) = 9√3.

Now, if the base of the triangle is b, then the height is b*sin (60 degrees), or

b*√3/2. Reworking the formula given above,

(1/2)(b)(√3*b/2) = 9√3

Simplify this by dividing both sides by √3:

b^2

= 9, or b^2 = 36, or b = 6

4

The equilateral triangle has side length 6 (i. e., all three sides are of length 6).

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