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Triangles and Trigonometry — Digital SAT SAT Math revision notes

A 3-page visual revision sheet for Triangles and Trigonometry, written for Digital SAT SAT Math. Formulas, diagrams and the traps that cost marks, laid out to be read the night before rather than the term before. Free, and it opens inside CapCompass.

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Triangles and Trigonometry in one look

three ratios, two special shapes, and a list of triples worth knowing

Every ratio is measured from ONE angle

  • opposite and adjacent are not properties of a side. They are relative to the angle you picked, and they swap the moment you switch to the other acute angle
  • the hypotenuse never swaps. It is the longest side and it always faces the 90 degree corner
  • SOH CAH TOA: Sine is Opposite over Hypotenuse, Cosine is Adjacent over Hypotenuse, Tangent is Opposite over Adjacent
  • the two acute angles of a right triangle add to 90, which is why the sine of one equals the cosine of the other

The five lines this whole topic runs on

  • sine of the marked angle sin x=opp/hyp
  • cosine cos x=adj/hyp
  • tangent tan x=opp/adj
  • Pythagoras, with c the hypotenuse a^2+b^2=c^2
  • complementary angles, the one identity you need sin x=cos(90°-x)

Worked: sine, cosine and the complement

Q. in triangle PQR the angle at Q measures 90°. If sin(P)=4/5, what is cos(R)?

  1. the three angles total 180 and Q takes 90, so P+R=90. The two acute angles are complementary
  2. that makes R=90°-P
  3. cos(R)=cos(90°-P), and cosine of the complement is sine of the angle itself
  4. so cos(R)=sin(P)=4/5

Answer: cos(R)=4/5

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What this Triangles and Trigonometry sheet covers

Open the full Triangles and Trigonometry sheet →Free, works offline, no account needed. All 3 pages, plus a study plan built around your own exam dates.

How CapCompass uses this sheet

These notes are not a standalone PDF. CapCompass plans SAT Math chapter by chapter against your real exam dates and free hours, and when the plan reaches Triangles and Trigonometry the sheet opens inside the study block itself — at the page covering the sub-topic that block is on, with the timer still running. Revision arrives at the moment the plan says revise, instead of having to be gone looking for.

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