Math Problem Statement

x = −3.00 cm, y = + 8.00 cm

What angle does the vector make with the +y-axis in counterclockwise direction? A positive angle is counterclockwise from the +y-axis.

Solution

Given the vector components x=3.00cmx = -3.00 \, \text{cm} and y=8.00cmy = 8.00 \, \text{cm}, we need to determine the angle it makes with the positive yy-axis, measured counterclockwise.

Step-by-Step Process:

  1. Determine the angle with the positive xx-axis:

    • The tangent of the angle relative to the positive xx-axis is given by: tan(θx)=yx=8.00cm3.00cm=2.67\tan(\theta_x) = \frac{y}{x} = \frac{8.00 \, \text{cm}}{-3.00 \, \text{cm}} = -2.67
    • Therefore, the angle relative to the xx-axis is: θx=tan1(2.67)\theta_x = \tan^{-1}(-2.67) Using a calculator: θx69.44\theta_x \approx -69.44^\circ
  2. Adjust the angle relative to the positive yy-axis:

    • The angle we found is measured clockwise from the negative xx-axis, which is equivalent to the angle from the positive yy-axis. The total angle in a full circle is 90θx90^\circ - \theta_x, as we are measuring counterclockwise from the yy-axis.

    Thus, the angle relative to the yy-axis is: θy=90(69.44)=90+69.44=159.44\theta_y = 90^\circ - (-69.44^\circ) = 90^\circ + 69.44^\circ = 159.44^\circ

Thus, the vector makes an angle of 159.44° with the positive yy-axis in the counterclockwise direction.

Would you like more details, or do you have any questions?

Related questions:

  1. What would be the angle if the vector had a positive xx-component?
  2. How does the quadrant of the vector affect the calculation of the angle?
  3. What is the magnitude of the vector with components (3.00cm,8.00cm)(-3.00 \, \text{cm}, 8.00 \, \text{cm})?
  4. What is the direction of the vector relative to the negative yy-axis?
  5. How would the angle change if both components were negative?

Tip: Always visualize vector direction when solving trigonometric problems to better understand angle orientation.

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Math Problem Analysis

Mathematical Concepts

Vector Components
Trigonometry
Coordinate Geometry

Formulas

tan(θ) = opposite / adjacent
θ = arctan(y / x)
Angle relative to y-axis = 90° + θ_x

Theorems

Inverse Tangent Function
Angle Measurement in Coordinate Plane

Suitable Grade Level

Grades 10-12