It's best to draw a picture first. Draw a line from the origin 6.5 cm long at an angle of 160°. Draw a second line from the origin, 10.5 cm long, at an angle of 295°. Draw a third line connecting the ends of these two lines, and label it 'c'. Label the central angle 'C', label the shorter of the two lines 'a', and the longer line 'b'.
The angle (C) between both aircraft is (180 - 70) + 25 = 110 + 25 = 135°.
Let a = 210, b = 130, C = 135°. Then, using the Law of Cosines
c² = a² + b² - 2abCos(C)
c² = 130² + 210² - 2(130)(21)(cos 135)
c² = 16900 + 44100 - 54600(-0.7071)
c² = 99608
c = 315.6
The two aircraft are 316 miles apart.
The angle (C) between both aircraft is (180 - 70) + 25 = 110 + 25 = 135°.
Let a = 210, b = 130, C = 135°. Then, using the Law of Cosines
c² = a² + b² - 2abCos(C)
c² = 130² + 210² - 2(130)(21)(cos 135)
c² = 16900 + 44100 - 54600(-0.7071)
c² = 99608
c = 315.6
The two aircraft are 316 miles apart.