Answer:
The plane is 388 miles far from the airport.
Step-by-step explanation:
We know that, the angle between southeast and south directions is [tex]135^\circ[/tex].
The plane travels as per the triangle as shown in the attached image.
A is the location of airport.
First it travels for 210 miles southeast from A to B and then 210 miles south from B to C.
[tex]\angle ABC = 135^\circ[/tex]
To find:
Side AC = ?
Solution:
As we can see, the [tex]\triangle ABC[/tex] is an isosceles triangle with sides AB = BC = 210 miles.
So, we can say that the angles opposite to the equal angles in a triangle are also equal. [tex]\angle A = \angle C[/tex]
And sum of all three angles of a triangle is equal to [tex]180^\circ[/tex].
[tex]\angle A+\angle B+\angle C = 180^\circ\\\Rightarrow \angle A+135^\circ+\angle A = 180^\circ\\\Rightarrow \angle A = \dfrac{1}{2} \times 45^\circ\\\Rightarrow \angle A =22.5^\circ[/tex]
Now, we can use Sine Rule:
[tex]\dfrac{a}{sinA} = \dfrac{b}{sinB}[/tex]
a, b are the sides opposite to the angles [tex]\angle A and \angle B[/tex] respectively.
[tex]\dfrac{210}{sin22.5^\circ} = \dfrac{b}{sin135^\circ}\\\Rightarrow \dfrac{210}{sin22.5^\circ} = \dfrac{b}{cos45^\circ}\\\Rightarrow b = 210\times \dfrac{1}{\sqrt2 \times 0.3826}\\\Rightarrow b = 210\times \dfrac{1}{0.54}\\\Rightarrow b \approx 388\ miles[/tex]
So, the answer is:
The plane is 388 miles far from the airport.
