Linked from

The 16 pages that link to Cosine, each with the reason it gives.

• Law of cosinesNarrower topic: The law uses cosine to encode the effect of an included angle.

• SineRelated: Cosine is sine shifted by one quarter of a cycle.

• Euler's formulaRelated: It supplies the real coordinate of the complex exponential.

• Trigonometric functionsBroader topic: Its phase-shift relation to sine links horizontal and vertical circular motion.

• TrigonometryBroader topic: It is the adjacent-to-hypotenuse ratio in a right triangle.

• Unit circleBroader topic: The point's horizontal position at angle θ is cos θ.

• Chebyshev polynomialsRelated: The defining identity expresses Tₙ as a multiple-angle cosine in disguise.

• Inverse trigonometric functionsRelated: Arccosine recovers a principal angle from a cosine value.

• TangentRelated: Its zeros create tangent’s vertical asymptotes.

• Euler's identityRelated: At π its value is −1, so Euler's formula yields e^{iπ} = −1.

• Trigonometric identityRelated: It completes the fundamental relation with sine: their squared values sum to one.

• Cosine similarityNarrower topic: The score is the cosine of the angle separating the vectors.

• Squeeze theoremRelated: Near zero, cosine provides one side of the bounds used in the sine-limit proof.

• Bretschneider's formulaBroader topic: Its value on the opposite-angle sum controls the noncyclic correction.

• History of trigonometryRelated: Cosine emerged through related astronomical calculations and became a partner to sine.

• Inverse Pythagorean theoremRelated: A zero cosine identifies the angle as 90 degrees in the law-of-cosines proof.