Question

proof that sin x cos A ( tan A -cotA) = 2 sin²A -1 ​

Answer 1

$sinacosa(tana - cota) \\ \\ = sinacosa( \frac{ {sin}^{2} a - {cos}^{2} a}{sinacosa} ) \\ \\ = {sin}^{2} a - {cos}^{2} a \\ \\ = {sin}^{2} a - 1 + {sin}^{2} a \\ \\ = 2 {sin}^{2} a - 1$