PreCal (verifying trig identities)
posted by Crystal .
How would you verify the identity?
sin^1/2xcosxsin^5/2xcosx=cos^3xradsinx

what is rad?

radical

multiply both sides by the sqrt sinx
sinxcosxsinxsin^3x cosx=cos^3x sinx
sinxcosxsinx(1cos^2x)sinxcosx=
sinx(1cosx)sinxcosx+sinxcox^3x=
sinx(1cosxcosx)+sinx cox^3x=
Hmmm. This is telling me the identity does not exist, because sinx(12cosx) is not zero.
check my work. There has to be an error here, but I am certain this is (was ) leading somewhere. 
I read your identity as
(sinx)^(1/2)  cosx  (sinx)^(5/2)*cosx = (cosx)^3 *(sinx)^(1/2)
I picked 30 degrees, and the
left side was NOT equal to the right side.
So the way you typed it, it is not an identity. 
Thanks, Reiny.

I think I have the same book as you Crystal... I have no clue how to solve this thing... :p
Respond to this Question
Similar Questions

math (trig)
i have some problems doing trig the first one is: Show that cos(x/2) sin(3x/2) = ½(sinx + sin2x) i know that you are supposed to substitute all those trig function things in it but i kind of forgot how to the only that i can see substituting … 
precal
Simplify the given expression........? (2sin2x)(cos6x) sin 2x and cos 6x can be expressed as a series of terms that involve sin x or cos x only, but the end result is not a simplification. sin 2x = 2 sinx cosx cos 6x = 32 cos^6 x 48 
verifying trigonometric identities
How do I do these problems? Verify the identity. a= alpha, b=beta, t= theta 1. (1 + sin a) (1  sin a)= cos^2a 2. cos^2b  sin^2b = 2cos^2b  1 3. sin^2a  sin^4a = cos^2a  cos^4a 4. (csc^2 t / cot t) = csc t sec t 5. (cot^2 t / csc 
TRIG!
Posted by hayden on Monday, February 23, 2009 at 4:05pm. sin^6 x + cos^6 x=1  (3/4)sin^2 2x work on one side only! Responses Trig please help!  Reiny, Monday, February 23, 2009 at 4:27pm LS looks like the sum of cubes sin^6 x + cos^6 … 
PreCal
1) Verify the identity cos^2 B  sin^2 B = 2 cos^2 B 1 I know that cos^2 B  sin^2 B = 2 cos^2 B 1 by the double angle formula but I do not know how to show this. 
pre cal verifying identities
how do I verify?? sin(x)+cos3(x)=sin(x)3cos(x)+4cos^(3)x 
Trig Identities
Proving identities: 1) 1+ 1/tan^2x = 1/sin^2x 2) 2sin^2 x1 = sin^2x  cos^2x 3) 1/cosx  cosx = sin x tan x 4) sin x + tan x =tan x (1+cos x) 5) 1/1sin^2x= 1+tan^2 x How in the world do I prove this...please help... I appreciateyour … 
Precal
Verify the identity: sin^(1/2)x*cosx  sin^(5/2)*cosx = cos^3x sq root sin x I honestly have no clue how to approach the sin^(5/2)*cosx part of the equation 
Precalculus/Trig
I can't seem to prove these trig identities and would really appreciate help: 1. cosx + 1/sin^3x = cscx/1  cosx I changed the 1: cosx/sin^3x + sin^3x/sin^3x = cscx/1cosx Simplified: cosx + sin^3x/sin^3x = cscx/1cosx I don't know … 
Trig Identities
Prove the following identities: 13. tan(x) + sec(x) = (cos(x)) / (1sin(x)) *Sorry for any confusing parenthesis.* My work: I simplified the left side to a. ((sinx) / (cosx)) + (1 / cosx) , then b. (sinx + 1) / cosx = (cos(x)) / (1sin(x)) …