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=□∘
Calculate tangent: To find the direction angle of u, we need to use the arctangent function, which gives us the angle whose tangent is the quotient of the y-coordinate and the x-coordinate of the vector.
Find arctangent: First, let's calculate the tangent of the direction angle, which is the y-coordinate divided by the x-coordinate of u. So, tan(θ)=−93.
Calculate angle: Now, we calculate tan(θ)=(−9)3=−31.
Adjust for quadrant: Next, we use the arctangent function to find the angle. So, θ=arctan(−31). We'll use a calculator for this.
Adjust for quadrant: Next, we use the arctangent function to find the angle. So, θ=arctan(−31). We'll use a calculator for this.After using the calculator, we find that θ≈arctan(−31)≈−18.43∘.
Adjust for quadrant: Next, we use the arctangent function to find the angle. So, θ=arctan(−31). We'll use a calculator for this.After using the calculator, we find that θ≈arctan(−31)≈−18.43∘.However, we want the direction angle to be between 0∘ and 360∘. Since our vector is in the second quadrant (negative x and positive y), we add 180∘ to the angle we found.
Adjust for quadrant: Next, we use the arctangent function to find the angle. So, θ=arctan(−31). We'll use a calculator for this.After using the calculator, we find that θ≈arctan(−31)≈−18.43∘.However, we want the direction angle to be between 0∘ and 360∘. Since our vector is in the second quadrant (negative x and positive y), we add 180∘ to the angle we found.So, θ=−18.43∘+180∘=161.57∘.
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