confused with angles

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• Sep 28th 2008, 12:36 AM
yzc717
confused with angles
• Sep 28th 2008, 02:29 AM
shailen.sobhee
(b)
Without calculations, since the three vectors have magnitude 3.00, you can deduce that the three angles will be 60 degrees each.

However, you also know that since B points downwards, it goes beyond the x-axis. Since the angle at the origin is 60 degrees and the angle that A makes with the positive direction of the x-axis is 30 degrees, you can deduce that the angle that the resultant makes with the positive direction of the x-axis is (60-30) degrees = 30 degrees.

You get me here?

Now, if you move the resultant to the origin, you will notice that the origin makes an angle of (180-30) degrees = 150 degrees with the +ve direction of the x-axis.

Since the question asks you to report all angles counterclockwise from the positive x axis, you simply start from the x-axis, and move counterclockwise until you reach your resultant.

The answer is 150 degrees.