Sketch the situation if necessary and use related rates to solve. two airplanes are flying in the air at the same height. airplane a is flying east at 250 mph and airplane b is flying north at 300 mph. if they are both heading to the same airport, located 30 miles east of airplane a and 40 miles north of airplane b, at what rate (in mph) is the distance between the airplanes changing?

  -390 mph

Step-by-step explanation:

Let a and b represent, respectively, the distances of A and B from the airport. The distance d between the planes is then given by the Pythagorean theorem as ...

  d² = a² + b²

Differentiating with respect to time, we have ...

  2d·d' = 2a·a' +2b·b'

Solving for d', we get ...

  d' = (a/d)a' +(b/d)b'

The value of d at the time of interest is ...

  d = √(a² +b²) = √(30² +40²) = √2500 = 50

Then the rate of change of separation is ...

  d' = (30/50)(-250 mph) +(40/50)(-300 mph) = (-150 -240) mph

  d' = -390 mph

The distance between planes is decreasing at 390 miles per hour.

2.2°  

step-by-step explanation:

let θ = the angle of elevation.

tanθ =77/2020

tanθ = 0.038 12

      θ = tan⁻¹0.038 12

      θ = 2.2°

d. $180

step-by-step explanation:

if the dimensions of the room is 9ft by 12 ft, we have the area of the floor as,

so the area of the floor is 108 square feet, converting that into square yards we get,

the cost of carpet is $15 per square yard, therefore the cost of carpet for 12 square yards is,

hence, the cost of carpet is $180.

assuming the dimensions of the room be,

15 ft by 12 ft

so, the area of the floor of that room is,

we can convert 180 square feet into square yards, we know that,

1 sq ft = 0.111 sq yard

so, 180 square feet is,

so the area of floor is 20 square yards.

now, the cost of carpet is 15 dollars per square yard, therefore the cost of carpet for 20 square yards is,

so, it will cost $300.