[SOLVED] Trigonometric Identities

• October 7th 2008, 04:06 PM
something3k
[SOLVED] Trigonometric Identities
given cos2y = 2 - sec^2(y)/sec^2(y)

verify that each equation is an identity

my mind is very boggling right now so please can anyone help with the steps?
• October 7th 2008, 04:14 PM
skeeter

$cos(2\theta) = 2\cos^2\theta - 1$
• October 7th 2008, 04:32 PM
something3k
i am sorry but i'm still stuck because i dont know what to do from there on, i've tried different identities but i don't think its leading to the right one.
• October 7th 2008, 05:10 PM
skeeter
$\frac{2 - \sec^2{y}}{\sec^2{y}} =$

$\frac{2}{\sec^2{y}} - \frac{\sec^2{y}}{\sec^2{y}} =$

$2\cos^2{y} - 1$
• October 7th 2008, 05:13 PM
something3k
oohh..haha i guess i was thinking too hard and missed the simple steps.. thanks you very much (Clapping)