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vec(u)=(-10,-9)
Find the direction angle of 
vec(u). Enter your answer as an angle in degrees between 
0^(@) and 
360^(@) rounded to the nearest hundredth.

theta=◻" 。 "

u=(10,9) \vec{u}=(-10,-9) \newlineFind the direction angle of u \vec{u} . Enter your answer as an angle in degrees between 0 0^{\circ} and 360 360^{\circ} rounded to the nearest hundredth.\newlineθ= \theta=\square^{\circ}

Full solution

Q. u=(10,9) \vec{u}=(-10,-9) \newlineFind the direction angle of u \vec{u} . Enter your answer as an angle in degrees between 0 0^{\circ} and 360 360^{\circ} rounded to the nearest hundredth.\newlineθ= \theta=\square^{\circ}
  1. Calculate Ratio Arctangent: To find the direction angle of the vector u=(10,9) \vec{u} = (-10, -9) , we need to calculate the angle that this vector makes with the positive x-axis. The direction angle θ \theta can be found using the arctangent function (also known as the inverse tangent or atan), which gives us the angle whose tangent is the ratio of the y-coordinate to the x-coordinate of the vector.
  2. Convert Radians to Degrees: First, we calculate the arctangent of the ratio of the y-coordinate to the x-coordinate of the vector u \vec{u} . Since u=(10,9) \vec{u} = (-10, -9) , the ratio is 910 \frac{-9}{-10} . Using a calculator, we find that arctan(910) \arctan\left(\frac{-9}{-10}\right) gives us an angle in radians.
  3. Adjust for Quadrant: We convert the angle from radians to degrees because the question asks for the answer in degrees. To convert radians to degrees, we multiply by 180π \frac{180}{\pi} .
  4. Perform Calculation: The calculated angle will give us the angle relative to the positive x-axis, but since both the x and y coordinates of u \vec{u} are negative, u \vec{u} lies in the third quadrant. The arctangent function will give us an angle in the first quadrant, so we need to add 180180° to get the correct direction angle in the third quadrant.
  5. Add 180180 Degrees: Performing the calculation, we have θ=arctan(910)×180π+180° \theta = \arctan\left(\frac{-9}{-10}\right) \times \frac{180}{\pi} + 180° . Using a calculator, we find that θ42.01°+180° \theta \approx 42.01° + 180° .
  6. Round to Nearest Hundredth: Adding 180180° to 4242.0101°, we get θ222.01° \theta \approx 222.01° . This is the direction angle of vector u \vec{u} in the third quadrant, measured counterclockwise from the positive x-axis.
  7. Round to Nearest Hundredth: Adding 180180° to 4242.0101°, we get θ222.01° \theta \approx 222.01° . This is the direction angle of vector u \vec{u} in the third quadrant, measured counterclockwise from the positive x-axis.We round the direction angle to the nearest hundredth as the question asks. Therefore, the direction angle of vector u \vec{u} is approximately 222222.0101°.

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