Question

докажите равновесие

Answer 1

$\dfrac{(cos15 \beta +cos \beta)+cos7 \beta }{sin7 \beta +(sin15 \beta -sin \beta)} = ctg7 \beta \\ \dfrac{2cos8 \beta cos 7\beta+cos7 \beta }{sin7 \beta +2cos8 \beta sin 7\beta} = ctg7 \beta \\ \dfrac{cos7 \beta( 2cos 8\beta+1) }{sin7 \beta( 2cos 8\beta+1)} = ctg7 \beta$
$\dfrac{cos7 \beta }{sin7 \beta} = ctg7 \beta \\ ctg7 \beta= ctg7 \beta$
Доказано.