$\"\"$

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The points of triangle are $\"\"$ .

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Let u be the vector from $\"\"$ to $\"\"$ as follows:

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$\"\"$ (Write component form of vector)

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$\"\"$ (Substitute: $\"\"$ )

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$\"\"$ (Simplify)

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$\"\"$ (Write magnitude formula)

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$\"\"$ (Substitute: $\"\"$ )

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$\"\"$ (Simplify) $\"\"$

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Let v be the vector from $\"\"$ to $\"\"$ as follows:

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$\"\"$ (Write component form of vector)

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$\"\"$ (Substitute: $\"\"$ )

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$\"\"$ (Simplify)

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$\"\"$ (Write magnitude formula)

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$\"\"$ (Substitute: $\"\"$ )

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$\"\"$ (Simplify) $\"\"$

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Let w be the vector from $\"\"$ to $\"\"$ as follows:

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$\"\"$ (Write component form of vector)

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$\"\"$ (Substitute: $\"\"$ )

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$\"\"$ (Simplify)

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$\"\"$ (Write magnitude formula)

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$\"\"$ (Substitute: $\"\"$ )

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$\"\"$ (Simplify) $\"\"$

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The vectors are $\"\"$ .

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The angle C between these vectors is $\"\"$ .

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$\"\"$ (Apply dot product: $\"\"$ )

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$\"\"$ (Substitute $\"\"$ )

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$\"\"$ (Simplify)

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$\"\"$ (Simplify)

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$\"\"$ (Multiply each side by $\"\"$ )

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$\"\"$ (Use calculator) $\"\"$

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The vectors are $\"\"$ .

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The angle B between these vectors is $\"\"$ .

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$\"\"$ (Apply dot product: $\"\"$ )

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$\"\"$ (Substitute

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$\"\"$ )

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$\"\"$ (Simplify)

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$\"\"$ (Simplify)

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$\"\"$ (Multiply each side by $\"\"$ )

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$\"\"$ (Use calculator)

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The remaining angle $\"\"$ . $\"\"$

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The interior angles of triangle are $\"\"$ .