Here's the question you clicked on:
lala2
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law of cosines: \[c^2 = a^2 + b^2 - 2abcos(\theta)\] c is the longest side, notice that pythagoras' is the special case of law of cosines, where theta = 90. \[165^2 = 83^2 + 111^2 - 2(83)(111)\cos(\theta)\]
you end up with: cos(theta) = 0.434983175 so with your calculator, use the cos^(-1) button on 0.434983175 (cos inverse) to get the obtuse angle: 64.2 degrees the direction north of west would be 180 degrees - 64.2 degrees
Re-reading the question, they want the angle "degrees North of West"
Euler lost a minus sign the angle you want plus 115.8 add up to a straight line
answer + 115.8 =180 solve for answer
I would add -115.8 to both sides
yes, the ship was heading west (270 degrees) and it turned 64.2º toward the north.