Question

use the double angle identities to rewrite sin^2(x) in terms of linear powers of common trig functions

Answer 1

\[\cos(2x) = 1-2\sin^{2} x\]
work backwards

Answer 2

@dumbcow where did the 2 in front of the sin come from?

Answer 3

\[\cos(2x) = \cos^{2} x - \sin^{2} x = (1-\sin^{2} x) -\sin^{2} x = 1-2\sin^{2} x\]

Answer 4

@dumbcow ok but how did you get the cos(2x) from just sin^2 x?

Answer 5

trig identities :) ....get a reference sheet, there a lot of trig identities to remember
look up double angle identities for cosine and the 1 i posted will come up

Answer 6

is it sin^2x=(1-cos2x)/2

Answer 7

yep

Answer 8

if you want to know where the identity came from ....look up angle sum formula for cos
cos(2x) = cos(x+x) = cos^2 x - sin^2 x

Answer 9

ok thanks! what does it mean by "in terms of linear powers of common trig functions" how will i know when ive found the answer?

Answer 10

@dumbcow

Answer 11

oh thats fancy language meaning answer only has sin/cos/tan with no powers

Answer 12

ok does the cos2x count?

Answer 13

yes because its cos to first power...doesn't matter if its 2x or 3x inside parenthesis

Answer 14

ok! im stuck after cos2x=1-sin^2x i dont know how to get rid of the sin^2x

Answer 15

?? you already did it
\[\sin^{2} x = \frac{1-\cos(2x)}{2}\]

Answer 16

oh thats all it was asking?!

Answer 17

yep

Answer 18

oh lol