Q. u=(−2,5)Find the direction angle of u. Enter your answer as an angle in degrees between 0∘ and 360∘ rounded to the nearest hundredth.θ=□∘
Identify Formula: Identify the formula for the direction angle of a vector. The direction angle θ of a vector u=(x,y) can be found using the arctangent function: θ=arctan(xy). However, since arctan only gives values from −90∘ to 90∘, we need to adjust the angle based on the quadrant in which the vector lies.
Calculate Arctangent: Calculate the arctangent of the y-coordinate divided by the x-coordinate.For u=(−2,5), we have x=−2 and y=5. Thus, θ=arctan(−25)=arctan(−2.5).Using a calculator, we find that arctan(−2.5)≈−68.20∘.
Adjust Based on Quadrant: Adjust the angle based on the quadrant.Since the x-coordinate is negative and the y-coordinate is positive, u lies in the second quadrant. In the second quadrant, we must add 180∘ to the arctangent value to find the correct direction angle.Therefore, θ=−68.20∘+180∘=111.80∘.
Ensure Angle Range: Ensure the angle is within the range 0∘ to 360∘. The calculated angle, 111.80∘, is already within the desired range. Therefore, no further adjustments are needed.