Q. u=(−9,3)Find the direction angle of u. Enter your answer as an angle in degrees between 0∘ and 360∘ rounded to the nearest hundredth.θ=□∘
Use Arctangent Function: To find the direction angle of the vectoru with components (−9,3), we need to use the arctangent function, which gives us the angle whose tangent is the ratio of the y-component to the x-component of the vector. The formula for the direction angle θ is θ=arctan(xy). However, since the vector is in the second quadrant (x is negative and y is positive), we need to add 180 degrees to the angle we get from the arctangent function to get the correct direction angle.
Calculate Arctangent: First, calculate the arctangent of the ratio of the y-component to the x-component of the vector u. The y-component is 3 and the x-component is −9. So, arctan(−93)=arctan(−31).
Find Correct Angle: Using a calculator, we find that arctan(−31) is approximately −18.43 degrees. Since the arctangent function can return values between −90 and 90 degrees, and our vector is in the second quadrant, we need to add 180 degrees to this value to find the correct direction angle.
Add 180 Degrees: Adding 180 degrees to −18.43 degrees gives us 161.57 degrees. This is the direction angle of the vector u in the range of 0 to 360 degrees.
More problems from Inverses of sin, cos, and tan: degrees