plsss help me and I will mark u as brainliest plssss help

Answer:
In my sketch the angle between their flights is 135°
So wouldn't we just have the cosine law??
Step-by-step explanation:
x^2 = 120^2 + 150^2 - 2(120)(150)cos135°
carry on, take care with the cos135, since it will be negative