Trigonometric Formulas Reference
Comprehensive reference of trigonometric formulas: basic identities, sum and difference, double angle, half angle, product-to-sum, and sum-to-product formulas.
Basic Identities
sin²α + cos²α = 1
tanα = sinα / cosα
cotα = cosα / sinα
1 + tan²α = 1 / cos²α
1 + cot²α = 1 / sin²α
tanα × cotα = 1
Sum and Difference Formulas
sin(α + β) = sinα·cosβ + cosα·sinβ
sin(α − β) = sinα·cosβ − cosα·sinβ
cos(α + β) = cosα·cosβ − sinα·sinβ
cos(α − β) = cosα·cosβ + sinα·sinβ
tan(α + β) = (tanα + tanβ) / (1 − tanα·tanβ)
tan(α − β) = (tanα − tanβ) / (1 + tanα·tanβ)
Double Angle Formulas
sin 2α = 2·sinα·cosα
cos 2α = cos²α − sin²α
cos 2α = 2cos²α − 1
cos 2α = 1 − 2sin²α
tan 2α = 2tanα / (1 − tan²α)
Half Angle Formulas
sin(α/2) = ±√((1 − cosα) / 2)
cos(α/2) = ±√((1 + cosα) / 2)
tan(α/2) = sinα / (1 + cosα)
tan(α/2) = (1 − cosα) / sinα
Product-to-Sum Formulas
sinα·sinβ = ½[cos(α−β) − cos(α+β)]
cosα·cosβ = ½[cos(α−β) + cos(α+β)]
sinα·cosβ = ½[sin(α+β) + sin(α−β)]
Sum-to-Product Formulas
sinα + sinβ = 2·sin((α+β)/2)·cos((α−β)/2)
sinα − sinβ = 2·cos((α+β)/2)·sin((α−β)/2)
cosα + cosβ = 2·cos((α+β)/2)·cos((α−β)/2)
cosα − cosβ = −2·sin((α+β)/2)·sin((α−β)/2)
How to Use the Trigonometric Formulas Reference
- Browse the reference table to find the values you need.
- Use search or scroll to locate specific entries.
- Click on a value to copy it or see more details.
- Use the table as a quick reference during calculations or study.
Referência Rápida
| De | Para |
|---|---|
| 1 × 1 | 1 |
| 5 × 5 | 25 |
| 7 × 8 | 56 |
| 9 × 9 | 81 |
| 12 × 12 | 144 |
| 15 × 15 | 225 |
Casos de Uso
- •Quick lookup of values during math class or professional work.
- •Verifying calculations without needing a full scientific calculator.
- •Studying mathematical relationships, patterns, and properties.
- •Using as a handy reference during engineering or science tasks.
Fórmula
Trigonometric identities are equations involving trig functions that hold true for all valid input values.
Perguntas Frequentes
What is the most fundamental trig identity?
The Pythagorean identity: sin²α + cos²α = 1. All other identities can be derived from this and the definitions.
What are the sum formulas used for?
Sum and difference formulas let you find exact values of trig functions for non-standard angles, e.g., sin(75°) = sin(45° + 30°).
What are double angle formulas?
They express trig functions of 2α in terms of α: sin 2α = 2sinα cosα, cos 2α = cos²α − sin²α.
When are product-to-sum formulas useful?
They convert products of trig functions into sums, simplifying integration and signal processing calculations.