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z=5-3i
Find the angle theta (in degrees) that z makes in the complex plane.
Round your answer, if necessary, to the nearest tenth. Express theta between -180^(@) and 180^(@).
theta=◻^(@)

z=53iz=5-3i\newlineFind the angle θ\theta (in degrees) that zz makes in the complex plane.\newlineRound your answer, if necessary, to the nearest tenth. Express θ\theta between \newline180-180^\circ and 180180^\circ.\newlineθ=\theta=\square^\circ

Full solution

Q. z=53iz=5-3i\newlineFind the angle θ\theta (in degrees) that zz makes in the complex plane.\newlineRound your answer, if necessary, to the nearest tenth. Express θ\theta between \newline180-180^\circ and 180180^\circ.\newlineθ=\theta=\square^\circ
  1. Calculate Argument: To find the angle θ\theta that the complex number z=53iz = 5 - 3i makes in the complex plane, we need to calculate the argument of the complex number, which is the angle formed with the positive xx-axis (real axis).
  2. Use Arctan Function: The argument of a complex number z=a+biz = a + bi is given by θ=arctan(ba)\theta = \arctan(\frac{b}{a}), where aa is the real part and bb is the imaginary part of the complex number. For z=53iz = 5 - 3i, a=5a = 5 and b=3b = -3.
  3. Check Angle Range: We calculate θ=arctan(35)\theta = \arctan(-\frac{3}{5}). Using a calculator, we find that arctan(35)30.96\arctan(-\frac{3}{5}) \approx -30.96 degrees. However, we need to ensure that the angle is expressed between 180-180 degrees and 180180 degrees.
  4. Determine Quadrant: Since the complex number 53i5 - 3i is located in the fourth quadrant of the complex plane (because the real part is positive and the imaginary part is negative), the angle we found is already in the correct range. Therefore, we do not need to adjust the angle.
  5. Round to Nearest Tenth: We round the angle to the nearest tenth, which gives us θ30.9631.0\theta \approx -30.96 \approx -31.0 degrees.

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