Two functions f(x) and g(x) are identically equal if, for every value of x in their domains
The equation representing this is called an identity.
It is often necessary to establish whether or not an equation involving two trigonometric equations is an identity.
To establish an identity, choose one side of the given equation and manipulate it using known identities until it has been transformed into the other side, or until it cannot be manipulated further.
Try these exercises:
Verify the identities.
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