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101.
Product of sine and cosine
$\sin\alpha \cdot \cos \beta = \dfrac{1}{2} \left[ \sin(\alpha-\beta) + \sin(\alpha + \beta) \right]$
102.
Product of tangents
$\tan\alpha \cdot \tan\beta = \dfrac{\tan \alpha + \tan \beta}{\cot \alpha + \cot \beta}$
103.
Product of cotangents
$\cot\alpha \cdot \cot\beta = \dfrac{\cot \alpha + \cot \beta}{\tan \alpha + \tan \beta}$
104.
Product of tangent and cotangents
$\tan\alpha \cdot \cot\beta = \dfrac{\tan\alpha + \cot\beta}{\cot\alpha+\tan\beta}$
115.
Set distributivity
$A \cup \left(B \cap C\right) = \left(A \cup B \right) \cap \left(A \cup C \right)$
116.
Set distributivity
$A \cap \left(B \cup C\right) = \left(A \cap B \right) \cup \left(A \cap C \right)$