How deeply does D3.js in Action, Third Edition cover trigonometry?

Derives sine and cosine coordinates from a right triangle, then applies radians and coordinate-system direction in code.

Trigonometry

As explained in D3.js in Action, Third Edition

Trigonometry is the branch of mathematics that relates angles to lengths and coordinates in geometric figures.

Trigonometry relates angles to positions and lengths. In a radial visualization, it converts each month’s angle and circle radius into the endpoint of an SVG axis. section 14.5.1

For an axis forming a right-angled triangle:

Calculate the horizontal coordinate with x = radius × sin(θ). section 14.5.1
Calculate the vertical coordinate with y = −radius × cos(θ), accounting for SVG’s vertical direction. section 14.5.1
Map twelve months across 0 to 2π − 2π/12 radians so January sits at twelve o’clock. section 14.5.1

Radial month axes

A Svelte component uses d3-scale’s point scale for month angles, then assigns each SVG line an origin of (0, 0) and sine/cosine-derived endpoints.

How D3.js in Action, Third Edition covers it

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Also explained in

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Math for Web DesignTrigonometry is the branch of mathematics concerned with relationships among the sides and angles of triangles.

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Related concepts

cosine functionincludes · The cosine function is a periodic trigonometric function that maps a real number or angle to a value between −1 and 1.
sine functionincludes · The sine function is a periodic trigonometric function that maps a real number or angle to a value between −1 and 1.
tangentincludes · The tangent is a trigonometric function equal to the sine of an angle divided by its cosine when the cosine is nonzero.
mathematicskind of · Mathematics is the formal study of quantities, structures, space, change, patterns, and relationships through abstraction and logical reasoning.
Taylor seriesimplemented by · A Taylor series is a power series whose coefficients are determined by a function’s derivatives evaluated at a specified expansion point.
radial menuuses · A radial menu is a user interface menu whose items are arranged around a central point and selected from surrounding directions.

This explainer was generated by Manning's knowledge graph from the text of D3.js in Action, Third Edition. The section links point to the parts of the book it draws on.