Posted by Anonymous on Thursday, December 11, 2008 at 10:55pm.
Is there a formula for sin(x/3)?

Math/Trigonometry  Damon, Thursday, December 11, 2008 at 11:01pm
I do not think it is likely because it is impossible to trisect an angle exactly in geometry. Since you can not do that I do not know how you could make a construction of right triangles that would lead to a triangle with exactly 1/3 of the original angle in it.

Math/Trigonometry  Anonymous, Thursday, December 11, 2008 at 11:07pm
I guess you're right. I was looking forward to finding the value of the sin 1 (deg).

Math/Trigonometry  drwls, Thursday, December 11, 2008 at 11:18pm
There is the infinite series
sin (x/3) = x/3  (1/2)(x/3)^2
+ (1/6)(x/3)^3 + ...
(1)^n *1/n!* (x/3)^n
(n> infinity)
Damon has made a good argument that there may be no closed form equation for sin (x/3) in terms of trig functions of x.
I tired Googling sin(x/3) and found nothing

Math/Trigonometry  drwls, Thursday, December 11, 2008 at 11:24pm
For angles that small, the approximation sin x = x is very good. x must be in radians to use it.
Sin 1 degree = sin pi/180 radian
If you use the first term of the infinite series, that gives you pi/180 = 0.0174533...
The exact value is 0.174524...
Answer This Question
Related Questions
 trigonometry HELP pleasE!  these must be written as a single trig expression, ...
 tigonometry  expres the following as sums and differences of sines or cosines ...
 Trigonometry  Identities  If tan 2x =  24/7, where 90 degrees < x < 180...
 Trigonometry  Solve the equation for solutions in the interval 0<=theta<...
 Trigonometry  Use a doubleangle formula to rewrite the expression. 6 sin x cos...
 trigonometry  Use a compound angle formula for cosine to show that cos2x = cos^...
 Trigonometry  I need to prove that the following is true. Thanks. csc^2(A/2)=...
 Trigonometry  Use the trigonometric subtraction formula for sine to verify this...
 Trigonometry  Prove the identity sin(x+y+z)+sin(x+yz)+sin(xy+z)+ sin(xyz...
 Trigonometry  Solve each equation, giving a general formula for all of the ...
More Related Questions