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Express r = (12, 210°) in the form a i + b j....

Express r = (12, 210°) in the form a i + b j.

A.

6(-i + \sqrt{3} j)

B.

6(-\sqrt{3} i - j)

C.

6(i - \sqrt{3} j)

D.

6(i + \sqrt{3} j)

Correct answer is B

F = F \cos \theta i + F \sin \theta j

r = (12, 210°) = 12 \cos 210 i + 12 \sin 210 j

= - 6\sqrt{3} i - 6j

= 6(-\sqrt{3} i - j)