Cosine of the difference and sum of two numbers

Sine of the difference and sum of two numbers

Tangent of the difference and sum of two numbers

Few more derivations based on the above formulas

Formula to transform the product into sum or difference

Formula to transform the sum or difference into product

or

Value of trigonometric functions at in terms of values at

Value of trigonometric functions at in terms of values at

Value of trigonometric functions at in terms of values at

Values of trigonometrical functions at some important points

Law of Sines or Sine Rule

Law of Cosines

or

or

or

Projection Formula

Napier’s Analogy (law of tangents). In any , we have

Area of a Triangle

Solving trigonometric equations

Step 1: Find a value of , preferably between and or between and satisfying the given equation and call it

Step 2:

- If the equation is , then as a general solution
- If the equation is , then as a general solution
- If the equation is , then as a general solution