Question

cos3α/cosα - sin3α/sinα =-2
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Answer 1

$\frac{cos3a}{cosa}-\frac{sin3a}{sina}=\frac{sina\;cos3a-cosa\;sin3a}{cosa\;sina}=\\\\=\frac{-sin2a}{cosa\;sina}=\frac{-2sina\;cosa}{cosa\;sina}=-2$