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z=-3-8i
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=38i z=-3-8 i \newlineFind the angle θ \theta (in degrees) that z z makes in the complex plane.\newlineRound your answer, if necessary, to the nearest tenth. Express θ \theta between 180 -180^{\circ} and 180 180^{\circ} .\newlineθ= \theta=\square^{\circ}

Full solution

Q. z=38i z=-3-8 i \newlineFind the angle θ \theta (in degrees) that z z makes in the complex plane.\newlineRound your answer, if necessary, to the nearest tenth. Express θ \theta between 180 -180^{\circ} and 180 180^{\circ} .\newlineθ= \theta=\square^{\circ}
  1. Identify real and imaginary parts: Identify the real and imaginary parts of the complex number zz.z=38iz = -3 - 8i, where the real part is 3-3 and the imaginary part is 8-8.
  2. Calculate the argument of z: Calculate the argument of z, which is the angle θ\theta in the complex plane.\newlineThe argument of z is given by θ=arctan(imaginary partreal part)=arctan(83)\theta = \arctan(\frac{\text{imaginary part}}{\text{real part}}) = \arctan(\frac{-8}{-3}).
  3. Use calculator to find theta in radians: Use a calculator to find the value of θ\theta in radians.θ=arctan(8/3)=arctan(8/3)\theta = \text{arctan}(-8 / -3) = \text{arctan}(8 / 3).Since we need the angle in degrees, we will convert it after calculation.
  4. Convert radians to degrees: Convert the angle from radians to degrees. θ\theta in degrees = arctan(83)×(180π)\arctan(\frac{8}{3}) \times (\frac{180}{\pi}).
  5. Calculate theta in degrees: Calculate the angle θ\theta in degrees using a calculator.θ\theta in degrees arctan(83)×(180π)69.4\approx \arctan(\frac{8}{3}) \times (\frac{180}{\pi}) \approx 69.4^\circ. However, since both the real and imaginary parts of zz are negative, zz lies in the third quadrant, and the angle should be adjusted to be between 180-180^\circ and 180180^\circ.
  6. Adjust angle for correct quadrant: Adjust the angle for the correct quadrant.\newlineIn the third quadrant, the angle θ\theta should be negative and we add 180°180° to the calculated angle to get the angle in the correct range.\newlineθ=69.4°180°=110.6°\theta = 69.4° - 180° = -110.6°.

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