Using one of the Pythagorean trigonometric identities, sec 2 x = 1 tan 2 x Substituting this, sin 2x = (2tan x) /(1 tan 2 x) Therefore, the sin 2x formula in terms of tan is, sin 2x = (2tan x) /(1 tan 2 x) Great learning in high school using simple cues Indulging in rote learning, you are likely to forget concepts With Cuemath, youTrigonometric Identities Playlist https//wwwyoutubecom/watch?v=PkQikVV6Z1Q&list=PLJma5dJyAqrWhKGY6TxPDnE9tSt4PtWp&index=3(sin x cos x) 2 1 = 1 cos 2 x (tan x) 2 1 = 1 cos 2 x tan 2 x = 1 cos 2 x − 1 There aren't any terms or factors involving sin x in this formula, so let's make up another one An equivalent formula for tan 2 x is tan 2 x = 1 cos 2 x − 1 tan 2 x = 1 cos 2 x − sin 2 x sin 2 x tan 2 x = sin 2 x sin 2 x cos 2 x − sin 2 x cos 2 x sin 2 x cos 2 x
C4 Help Integrate 2sec 2xtanx The Student Room