9514 1404 393
Answer:
∠CAB = 86°
∠ABC = 43°
∠BCA = 51°
Step-by-step explanation:
This can be done a couple of different ways (as with most math problems). We can use the distance formula to find the side lengths, then the law of cosines to find the angles. Or, we could use the dot product. In the end, the math is about the same.
The lengths of the sides are given by the distance formula.
AB² = (4-1)² +(-3-0)² +(0-(-1)) = 16 +9 +1 = 26
BC² = (1-4)² +(2-(-3))³ +(3-0)² = 9 +25 +9 = 43
CA² = (1-1)² +(0-2)² +(-1-3)² = 4 +16 = 20
From the law of cosines, ...
∠A = arccos((AB² +CA² -BC²)/(2·AB·CA)) = arccos((26 +20 -43)/(2√(26·20)))
∠A = arccos(3/(4√130)) ≈ 86°
∠B = arccos((AB² +BC² -AC²)/(2·AB·BC)) = arccos((26 +43 -20)/(2√(26·43)))
∠B = arccos(49/(2√1118)) ≈ 43°
∠C = arccos((BC² +CA² -AB²)/(2·BC·CA)) = arccos((43 +20 -26)/(2√(43·20)))
∠C = arccos(37/(4√215)) ≈ 51°
The three angles are ...
∠CAB = 86°
∠ABC = 43°
∠BCA = 51°
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Additional comment
This sort of repetitive arithmetic is nicely done by a spreadsheet.
