Question

2. Expand:(sinA - 2cosA)2​

Answer 1

$\large ( {sinA - 2cosA})^{2} \\ \large = {sin}^{2} A + 4 {cos}^{2} A - 2sinA2cosA \\ \large = {sin}^{2} A + {cos}^{2} A + 3 {cos}^{2} A - 2.2sinA \: cosA \\ \large = 1 + 3 {cos}^{2} A - 2sin2A$