Table of contents
- 0. Functions7h 52m
- Introduction to Functions16m
- Piecewise Functions10m
- Properties of Functions9m
- Common Functions1h 8m
- Transformations5m
- Combining Functions27m
- Exponent rules32m
- Exponential Functions28m
- Logarithmic Functions24m
- Properties of Logarithms34m
- Exponential & Logarithmic Equations35m
- Introduction to Trigonometric Functions38m
- Graphs of Trigonometric Functions44m
- Trigonometric Identities47m
- Inverse Trigonometric Functions48m
- 1. Limits and Continuity2h 2m
- 2. Intro to Derivatives1h 33m
- 3. Techniques of Differentiation3h 18m
- 4. Applications of Derivatives2h 38m
- 5. Graphical Applications of Derivatives6h 2m
- 6. Derivatives of Inverse, Exponential, & Logarithmic Functions2h 37m
- 7. Antiderivatives & Indefinite Integrals1h 26m
- 8. Definite Integrals4h 44m
- 9. Graphical Applications of Integrals2h 27m
- 10. Physics Applications of Integrals 2h 22m
3. Techniques of Differentiation
Derivatives of Trig Functions
Problem 3.5.7
Textbook Question
Find an equation of the line tangent to the curve y = sin x at x = 0.

1
First, understand that the equation of a tangent line to a curve at a given point is given by the formula: y - y₁ = m(x - x₁), where m is the slope of the tangent line and (x₁, y₁) is the point of tangency.
To find the slope of the tangent line, calculate the derivative of the function y = sin(x). The derivative, y' = cos(x), gives the slope of the tangent line at any point x.
Evaluate the derivative at the point of tangency, x = 0. Substitute x = 0 into y' = cos(x) to find the slope m at x = 0.
Determine the y-coordinate of the point of tangency by substituting x = 0 into the original function y = sin(x). This gives y₁ = sin(0).
Substitute the values of m, x₁, and y₁ into the tangent line equation y - y₁ = m(x - x₁) to find the equation of the tangent line at x = 0.

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Key Concepts
Here are the essential concepts you must grasp in order to answer the question correctly.
Tangent Line
A tangent line to a curve at a given point is a straight line that touches the curve at that point without crossing it. The slope of the tangent line represents the instantaneous rate of change of the function at that point, which can be found using the derivative.
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Slopes of Tangent Lines
Derivative
The derivative of a function at a point quantifies how the function's output changes as its input changes. For the function y = sin x, the derivative, denoted as y', gives the slope of the tangent line at any point x, which is crucial for finding the equation of the tangent line.
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Derivatives
Point-Slope Form
The point-slope form of a linear equation is given by y - y1 = m(x - x1), where (x1, y1) is a point on the line and m is the slope. This form is particularly useful for writing the equation of the tangent line once the slope and the point of tangency are known.
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