♾️ap calculus ab/bc review

Horizontal Tangent Line

Written by the Fiveable Content Team • Last updated September 2025
Verified for the 2026 exam
Verified for the 2026 examWritten by the Fiveable Content Team • Last updated September 2025

Definition

A horizontal tangent line is a line that is parallel to the x-axis and touches a curve at a specific point without crossing it. It indicates that the slope of the curve at that point is zero.

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