SOLUTION: Hi, can someone help me in the 2nd part to find x.
Question:
By writing cos 4x = cos (3x+x) and cos 2x = cos (3x-x), show that cos 2x + cos 4x = 2cos3xcosx and cos 2x – cos 4x
Algebra.Com
Question 1056981: Hi, can someone help me in the 2nd part to find x.
Question:
By writing cos 4x = cos (3x+x) and cos 2x = cos (3x-x), show that cos 2x + cos 4x = 2cos3xcosx and cos 2x – cos 4x = 2sin3xsinx.
Given further that cos3xcosx = 0.683 and sin3xsinx = 0.183, find the value of x where 0° < x < 180°.
Thank you very much.
Answer by josgarithmetic(39630) (Show Source): You can put this solution on YOUR website!
-----------------------------------------------------
Using commutative property of equality,
Very straightforward if you know or have reference to the two identities.
--
The second part if you will look carefully, only depends on simple substitution. Note also that the sine information in not needed.
RELATED QUESTIONS
(cos 6x + 6 cos 4x + 15 cos 2x + 10)/
(cos 5x + 5 cos 3x + 10 cos x)
is equal... (answered by ikleyn)
Write cos^4(3x) in terms of cosines all to the 1st power. FIND LCD & SIMPLIFY!
I GOT... (answered by Alan3354)
Solve the following equations for 0deg <= x <= 360deg:
(i) cos 2x cos x = sin 4x sin x... (answered by ikleyn)
Find an equivalent expression for cos 3x in terms of powers of cos x.
cos 3x = cos (2x (answered by eggsarecool)
show that... (answered by Edwin McCravy)
cos x = cos 2x... (answered by ikleyn)
Show that: sin x cos^2x - sin x =... (answered by MathLover1)
sin(A+B) = sin A cos B + cos A sin B
cos(A+B) =... (answered by vleith)
For cos(x)cos(3x)-sin(x)sin(3x)=0, use an addition or subtraction formula to simplify the (answered by ikleyn)