Expert: Sherman D. - 6/20/2009

Question
QUESTION: verify the identity of cos^2x=1/2(cos2x+1)

ANSWER: i'm guessing you mean

cos(x)^2 = (1/2)(cos(2x) + 1)

cos(x)^2 = (1/2)(2cos(x)^2 - 1 + 1)

cos(x)^2 = (1/2)(2cos(x)^2)

cos(x)^2 = cos(x)^2

more info found at http://math2.org/math/trig/identities.htm

---------- FOLLOW-UP ----------

QUESTION: thank you. I have another question, can you also verify the identity of:
sin^2x/2=1-cosx/2
cos^2x/2=1+cosx/2

Answer
you should really work on your typing so i can better understand you.

if by this you mean
sin(x/2)^2 = 1 - cos(x/2)
cos(x/2)^2 = 1 + cos(x/2)

or

(sin(x)^2)/2 = 1 - cos(x/2)
(cos(x)^2)/2 = 1 + cos(x/2)

or

.....

there are like 4 possible ways i could take this.

i'm guessing you mean

sin(x/2)^2 = (1 - cos(x))/2
cos(x/2)^2 = (1 + cos(x))/2

if so, just check out www.sosmath.com/trig/douangl/douangl.html