GRE Subject Test: Math : Complex Plane

Study concepts, example questions & explanations for GRE Subject Test: Math

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Example Questions

Example Question #161 : Imaginary Numbers

Write the complex number  in polar form, where polar form expresses the result in terms of a distance from the origin  on the complex plane and an angle from the positive -axis, , measured in radians.

Possible Answers:

Correct answer:

Explanation:

To see what the polar form of the number is, it helps to draw it on a graph, where the horizontal axis is the imaginary part and the vertical axis the real part. This is called the complex plane.

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To find the angle , we can find its supplementary angle  and subtract it from  radians, so .

Using trigonometric ratios,    and  .

Then .

 

To find the distance , we need to find the distance from the origin to the point . Using the Pythagorean Theorem to find the hypotenuse  or .

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