Math Problem Statement

A wheel of radius one foot is placed so that its center is at the origin, and a paint spot

on the rim is at (1, 0). The wheel is spun 27 degrees in a counterclockwise direction. What are

the coordinates of the paint spot? What if the wheel is spun θ degrees instead?

Solution

Let's break down the problem step-by-step.

1. Initial Setup

  • The wheel has a radius of 1 foot.
  • The center is at the origin: (0, 0).
  • There is a paint spot initially at the coordinate (1, 0), which is on the rim of the circle.

2. Understanding the Rotation

When a point on the circle is rotated by an angle θ\theta (in degrees) in the counterclockwise direction, the new coordinates can be calculated using basic rotation formulas.

3. Rotation Formula

For a point (x,y)(x, y) on a circle centered at the origin, if rotated by an angle θ\theta counterclockwise, the new coordinates (x,y)(x', y') are given by:

x=xcosθysinθx' = x \cos \theta - y \sin \theta y=xsinθ+ycosθy' = x \sin \theta + y \cos \theta

4. Applying the Formula for θ=27\theta = 27^\circ

Initially, the paint spot is at (x,y)=(1,0)(x, y) = (1, 0). Substituting x=1x = 1 and y=0y = 0:

x=1cos270sin27=cos27x' = 1 \cdot \cos 27^\circ - 0 \cdot \sin 27^\circ = \cos 27^\circ

y=1sin27+0cos27=sin27y' = 1 \cdot \sin 27^\circ + 0 \cdot \cos 27^\circ = \sin 27^\circ

Therefore, after a rotation of 27 degrees, the coordinates of the paint spot are:

(cos27,sin27)(\cos 27^\circ, \sin 27^\circ)

5. General Formula for Any θ\theta

If the wheel is spun by an angle θ\theta in degrees, the coordinates of the paint spot become:

(cosθ,sinθ)(\cos \theta, \sin \theta)

This formula is derived from the rotation transformation for any given angle θ\theta.

6. Numerical Values for 27 Degrees

Calculating the cosine and sine values for 27 degrees:

  • cos270.8910\cos 27^\circ \approx 0.8910
  • sin270.4540\sin 27^\circ \approx 0.4540

Hence, the exact coordinates after a 27-degree rotation are approximately:

(0.8910,0.4540)(0.8910, 0.4540)

Summary

  • After a 27-degree rotation, the coordinates of the paint spot are (0.8910,0.4540)(0.8910, 0.4540).
  • For any general angle θ\theta, the coordinates are (cosθ,sinθ)(\cos \theta, \sin \theta).

Let me know if you'd like to explore this further or see more details!

Related Questions:

  1. What would the coordinates be if the wheel was rotated by 90 degrees?
  2. How does the formula change if the wheel is rotated in a clockwise direction?
  3. What happens if the paint spot was initially at (1,0)(-1, 0)?
  4. Can you derive the formula if the center of the circle is at (h,k)(h, k) instead of the origin?
  5. What are the coordinates of the paint spot if rotated by 180180^\circ?

Tip:

When dealing with rotations, always remember that counterclockwise rotation corresponds to positive angles and clockwise rotation to negative angles in trigonometric terms.

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Math Problem Analysis

Mathematical Concepts

Geometry
Trigonometry
Coordinate Rotation

Formulas

Rotation formula for coordinates: x' = x cos θ - y sin θ, y' = x sin θ + y cos θ
Cosine and Sine values for angle θ

Theorems

Rotation of points in the coordinate plane

Suitable Grade Level

Grades 10-12