Sir I can't understand"Fundamental identities" and "Domain and range of trigonometric functions"
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Answer:
FUNDAMENTAL IDENTITIES: f an equation contains one or more variables and is valid for all replacement values of the variables for which both sides of the equation are defined, then the equation is known as an identity. The equation x 2 + 2 x = x( x + 2), for example, is an identity because it is valid for all replacement values of x.
If an equation is valid only for certain replacement values of the variable, then it is called a conditional equation. The equation 3 x + 4 = 25, for example, is a conditional equation because it is not valid for all replacement values of x. An equation that is said to be an identity without stating any restrictions is, in reality, an identity only for those replacement values for which both sides of the identity are defined. For example, the identity
DOMAIN AND RANGE : The domain of a function is the specific set of values that the independent variable in a function can take on. The range is the resulting values that the dependant variable can have as x varies throughout the domain.