Respuesta :
Alright, lets get started.
Please refer the diagram I have attached.
Plane flies from point A to point B then point C.
We have a triangle in which two sides AB and BC known and the angle between these two lines.
We could use cosine law to find the third side AC
[tex] b^2 = a^2 + c^2 - 2 a c*cos B [/tex]
[tex] b^2 = 290^2 + 720^2 - 2 * 720 * 290 * cos 125 [/tex]
[tex] b^2 = 84100 + 518400 - 417600 cos 125 [/tex]
[tex] b^2 = 602500 - 417600 * (-0.5735) [/tex]
[tex] b^2 = 602500 + 239493.6 [/tex]
[tex] b^2 = 841993.6 [/tex]
Taking square root both sides
b = 917.6 miles
It means plane has to fly 917.6 miles from the second destination back to Dallas. : Answer
Hope it will help :)
