Question 1171766
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(i)   Take y2 = 2cos(x)   (the same as y1)



(ii) Take y2 = -2cos(x)   (opposite to y1)



(iii)  Regarding k1, k2, I do not understand their meaning - and, therefore, can not answer.


In part (iii), you post does not look like as a Math problem.