Past Papers’ Solutions | Cambridge International Examinations (CIE) | AS & A level | Mathematics 9709 | Pure Mathematics 2 (P2-9709/02) | Year 2003 | Oct-Nov | (P2-9709/02) | Q#4

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Question


i.       
Express  in the form , where  and , giving exact  value of .

ii.       Hence show that one solution of the equation

, and find the other solution in the interval 0 < θ < 2π.

Solution

     i.
 

We are given that;

We are required to write it in the form;

If  and  are positive, then;

 can be written in the for

 can be written in the for

where,

 and , , with

Considering the given equation, we have following case at hand;

 can be written in the for

Comparing it with given equation Therefore

Therefore;

Finally, we can find , utilizing the equation;

Using calculator we can find that;

Therefore;

   ii.
 

We are required to solve the equation;

As demonstrated in (i), we can write;

Therefore, we need to solve;

Using calculator we can find that;

To find the other solution in the interval  we utilize the odd/even property of .

Properties of

Domain

Range

Periodicity

Odd/Even

Translation/

Symmetry

We use odd/even property;

Therefore, we have two solutions (roots) of the equation;

To find all the solutions (roots) over the interval , we utilize the periodic property of    for both these values of .

Therefore;

But it is evident that this will yield values of  outside the given interval .

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