Trigonometric Algebra

[Guest]

Hello everyone and welcome to my first post! =)

I need to solve this equation for n:

0.01 = 36pi - 6sin(180/n)6cos(180/n)*n

Here's what I've done so far:

0.01 = 36(pi - n[sin(180/n)cos(180/n)]

0.01 / 36 - pi = - n [sin(180/n)cos(180/n)]

Then I used the inverses:

sin^-1(0.01/36 - pi) = -n (180/n) cos(180/n)

sin^-1(0.01/36 - pi) = -180 * cos(180/n)

cos^-1(sin^-1(0.01/36 - pi) = -180 * (180/n)

cos^-1(sin^-1(0.01/36 - pi) = -32400 /n

n = -32400 / cos^-1(sin^-1(0.01/36 - pi)

Unfortunatly, when I put this into my calculator, it gives me an error!
If anyone could help, I would definately appreciate it!

 

[tkhunny]

Same Answer Here:

What an odd equation. Is that 180º?

For starters, your LHS is not conducive to the inverse sine. \(\displaystyle \frac{0.01}{36}-\pi=-3.1414...[\tex] The inverse sine won't like that. This explains your error.

Maybe you could use this sin(2x) = 2*sin(x)cos(x)??

And, for the record, posting the same problem multiple times is not a good practice.\)