Question

A little help...?
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Answer 1

Răspuns:

$\frac{24}{25}$

Explicație pas cu pas:

$\sin^{2} (a) + \cos^{2} (a) = 1 \\ \cos^{2} (a) = \frac{16}{25} \\ \cos (a) = - \frac{4}{5} \\ \sin(2a) =2 \sin(a) \times \cos(a) \\ = 2 \times ( - \frac{3}{5} ) \times ( - \frac{4}{5} ) \\ = \frac{24}{25}$