Posted by **sqleung** on Saturday, March 1, 2008 at 1:52am.

Solve for x (exact solutions):

sin x - sin 3x + sin 5x = 0

-¦Ð ¡Ü x ¡Ü 0

------

Now, using my graphics calculator, I discovered that the following equation has 5 solutions. I have managed to come up with 3 of them but I'm having trouble finding the other 2. My 3 answers are:

0, -¦Ð/6, -5¦Ð/6

I need the answers to be EXACT like above so any help would be appreciated. Thankyou.

- Trig Equation -
**drwls**, Saturday, March 1, 2008 at 7:25am
I answered this question two days ago. Once of the answers is of course x = 0. For the others, I substitued indentities for sin 3x and sin 5x in terms of sin x, and ended up with a factorable equation for sin x. This leads to exact equations for arcsin in terms of fractions.

I am not able to read your terms -¦Ð/6 and -5¦Ð/6

If I can find my original answer, I will post a link to it below

- Trig Equation -
**drwls**, Saturday, March 1, 2008 at 7:46am
OK, I found my original answer at

http://www.jiskha.com/display.cgi?id=1204243109

and it has two mistakes, a missing exponent and an incorrect sign. I should have ended up with the equation

3sinx - 16 sin^3x + 16sin^5x = 0

which factors to

sinx (3 - 16sin^2x + 16sin^4x) = 0

sinx (4sin^2x-3)(4sin^2x -1) = 0

Thge roots, besides x=0, are:

sin^2x = 1/4

sin x = +/-sqrt(1/2)

and

sin^2 = (3/4)

sin x = +/-(sqrt3)/2

- Trig Equation -
**drwls**, Saturday, March 1, 2008 at 10:31am
Any positive or negative integral multiple of 30 degrees (x=pi/6), including 0 degrees, satisfies the equation.

## Answer This Question

## Related Questions

- Maths - Solve for x (exact solutions): sin x - sin 3x + sin 5x = 0 ¦Ð ¡Ü x...
- math - Eliminate the parameter (What does that mean?) and write a rectangular ...
- Trigonometry - Solve the equation for solutions in the interval 0<=theta<...
- TRIG! - Posted by hayden on Monday, February 23, 2009 at 4:05pm. sin^6 x + cos^6...
- tigonometry - expres the following as sums and differences of sines or cosines ...
- Math (Trig) - Solve the equation for exact values of x. sin(x) = 1-2(sin(x))^2
- MathsSs triG - Consider sin(x-360)sin(90-x)tan(-x)/cos(90+x) 1.A.SIMPLIFY sin(x-...
- Precalculs - I have no idea how to do these type of problems. -------Problem...
- trig - find the exact solutions (è in degrees) sin^2è+2cosè=-2 change the sin^2 ...
- Math(Please help) - Using the equation y=yo + (vo sin Q) t - 1/2gt^2 I have to ...

More Related Questions