Chapter 8. Introduction to Trigonometry
5 sections · about 20 pages in the Mathematics book (jemh108.pdf). Section anchors below are the targets of the citation chips you get back from an answer.
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Concept animations for this chapter
Interactive explanations, drawn in the page — no video, no external scripts. Each one is keyboard operable, has a “what to notice” caption, and a “try this” prompt that changes what it shows.
Trigonometric ratios on the unit circle
conceptId: trig-unit-circle
Trigonometric ratios on the unit circle
CBSE Class 10 Mathematics · Ch 8 §8.2 — the radius is 1, so the coordinates of P are (cos θ, sin θ).
- sin θ
- 0.574
- cos θ
- 0.819
- tan θ = sin θ / cos θ
- 0.700
- sin²θ + cos²θ
- 1.000000
What to notice: sin θ and cos θ are just the legs of a right triangle drawn inside a circle of radius 1 — as θ sweeps, sin θ rises to 1 at 90° and falls back, while cos θ does the opposite, and sin²θ + cos²θ stays pinned at 1.
Try this: set θ = 90° and read tan θ — cos θ is 0 there, so the ratio is undefined. Then try θ = 45° and compare sin θ with cos θ.
10 further animations in the registries belong to other chapters.