Question

1 – sina×ctga×cosa=
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Answer 1

Ответ:

$1 - \sin \alpha \times ctg \alpha \times \: cos \alpha = \\ 1 - sin \alpha \times \frac{cos \alpha }{sin \alpha } \times cos \alpha = \\ 1 - cos {}^{2} \alpha = sin {}^{2} \alpha$