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z=-8+5i
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=8+5i z=-8+5 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=8+5i z=-8+5 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 parts of zz: Identify the real and imaginary parts of the complex number zz.z=8+5iz = -8 + 5i, where the real part is 8-8 and the imaginary part is 55.
  2. Calculate 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(58)\theta = \arctan(\frac{\text{imaginary part}}{\text{real part}}) = \arctan(\frac{5}{-8}).
  3. Find theta in radians: Use a calculator to find the value of theta in radians. θ=arctan(58)arctan(0.625)\theta = \text{arctan}(\frac{5}{-8}) \approx \text{arctan}(-0.625).
  4. Convert angle to degrees: Convert the angle from radians to degrees. θarctan(0.625)×(180/π)\theta \approx \arctan(-0.625) \times (180 / \pi) degrees.
  5. Calculate angle in degrees: Calculate the angle in degrees, ensuring it is in the correct quadrant.\newlineSince the real part is negative and the imaginary part is positive, zz lies in the second quadrant. The arctan\text{arctan} function will give a negative result because the tangent is negative in the second quadrant. To find the angle in the second quadrant, we add 180180 degrees to the result.\newlineθarctan(0.625)×(180/π)+180\theta \approx \text{arctan}(-0.625) \times (180 / \pi) + 180 degrees.
  6. Perform calculation: Perform the calculation using a calculator.\newlineθarctan(0.625)×(180/π)+18032.0053832+180147.9946168\theta \approx \arctan(-0.625) \times (180 / \pi) + 180 \approx -32.0053832 + 180 \approx 147.9946168 degrees.
  7. Round to nearest tenth: Round the answer to the nearest tenth. θ148.0\theta \approx 148.0 degrees.

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