Use a linear approximation to estimate cos29

1. Linear approximation: Using the tangent line to approximate the value of a function near a specific point.
2. Trigonometric functions: Understanding the properties and behavior of trigonometric functions such as cosine and sine.
3. Derivatives: Knowing how to find the derivative of a function, in this case, the derivative of the cosine function.
4. Angle measurement: Understanding the concept of angles and their measurement in degrees or radians.
5. Algebraic manipulation: Performing basic algebraic operations to simplify expressions and solve for unknowns.