The video tutorial explains how to find horizontal tangent lines by setting the derivative of a function to zero. It covers the process of finding the derivative, solving for when the cosine of X equals -1, and determining the angle in radians. Finally, it calculates the coordinate points using the determined X value.

What is the significance of a horizontal tangent line in the context of derivatives?

• It marks the end of the function's domain.

• It represents a point where the derivative is zero.

• It shows where the function is undefined.

• It indicates a point of inflection.

What is the derivative of the function y = sin(x)?

• cos(x)

• -sin(x)

• -cos(x)

• sin(x)

When setting the derivative equal to zero, what equation do we solve for x?

• sin(x) = 1

• cos(x) = 1

• 1 + cos(x) = 0

• 1 + sin(x) = 0

At what angle in radians does the cosine value equal -1 on the unit circle?

• π/2

• π

• 2π

• 3π/2

What is the y-coordinate when x equals π and the sine of π is calculated?

• 1

• π

• -1

• 0