Page 33 - DMTH201_Basic Mathematics-1

Basic Mathematics – I

Notes
3. Determine the values of
(a) (b)

(c)

2.2 Trigonometric Functions and Submultplication of Angles

are called submultiples of A.

It has been proved that

Replacing A by we easily get the following formulae for the sub–multiple

We will choose either the positive or the negative sign depending on whether corresponding
value of the function is positive or negative for the value of This will be clear from the
following examples:
Examples 5: Find the values of

Solution: We use the formulae and take the positive sign, because

are both positive.

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