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Science-Related Homework Help Mathematics Topic started by: mickeylee on Oct 25, 2012



Title: Is there any way to find the inverse of a trigonometric function without a calculator?
Post by: mickeylee on Oct 25, 2012
Is there any way to find the inverse of a trigonometric function without a calculator? It is not those special angle types. It is something like tan -1 x = 0.529. I am actually expecting very complicated ways.


Title: Is there any way to find the inverse of a trigonometric function without a calculator?
Post by: firechoker on Oct 25, 2012
You have, for example, tan^-1 x = 0.529.

This means "the angle whose tan is 0.529.

You could use a Taylor expansion for tan:

tan^-1 x =  x - x^3/3 + x^5/5 - x^7/7 + ---

Just plug in 0.529 and you will get 0.48632 after 4 terms. The tan of 0.48632 (in radians, of course) is 0.5287


Title: Is there any way to find the inverse of a trigonometric function without a calculator?
Post by: ilikepoop on Oct 25, 2012
Every continuous and differentiable function, including the inverse trig functions, may be expressed as an infinite series of polynomials called a Taylor Series.  You could estimate this infinite series at say two terms, although the estimate may not be very good.