Arc SOHCAHTOA method
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04-02-2022, 12:10 AM
(This post was last modified: 04-15-2022 01:18 AM by Albert Chan.)
Post: #5
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RE: SOHCAHTOA, for arc-trig
For fun, I try the same idea to arc hyperbolics.
asinhq(x) = asinh(√x) = ln(√(x) + √(x+1)) acoshq(x) = acosh(√x) = ln(√(x) + √(x-1)) atanhq(x) = atanh(√x) = 1/2 * ln((1+√x) / (1-√x)) → asinhq(x) = acoshq(x+1) // O = x, A = 1+x, H = 1 This suggested for hyperbolics, A = O + H TOA suggested asinhq(x) = atanhq(x/(1+x)) Lets proof this by getting tanh(y = asinh(sqrt(x))) To simplify away the exponential, let z = e^y tanh(y) = (z-1/z) / (z+1/z) = (z^2-1) / (z^2+1) z = √(x) + √(x+1) // Goal, remove all square roots. z - √(x) = √(x+1) z^2 - 2*√(x)*z + x = x + 1 (z^2 - 1) = 2*√(x)*z (z^2-1)^2 = 4*x*z^2 If atanhq() expression is correct, we should have (z^2-1)/(z^2+1) = √(x/(1+x)) Or, (z^2-1)^2 * (1+x) = (z^2+1)^2 * x (z^2-1)^2 * (1+x) - (z^2+1)^2 * x = 1 - 2*z^2 + z^4 - 4*x*z^2 = (z^2-1)^2 - 4*x*z^2 = 0 QED Relative to atanhq(x), we have O = x, A = 1, H = A-O = 1-x SOH CAH atanhq(x) = asinhq(x/(1-x)) = acoshq(1/(1-x)) Update: I was being stupid, and should prove with more familiar sinh/cosh Or, simply work with sin/cos, then flip sign using Osborn's rule y = asinhq(x) → sinh(y)² = x → cosh(y)² = 1+x → tanh(y)² = x/(1+x) → y = atanhq(x/(1+x)) |
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Messages In This Thread |
Arc SOHCAHTOA method - Albert Chan - 03-31-2022, 09:50 PM
RE: soh-cah-toa, for arc-trig function - Albert Chan - 03-31-2022, 11:07 PM
RE: SOHCAHTOA, for arc-trig - Albert Chan - 04-01-2022, 05:49 PM
RE: SOHCAHTOA, for arc-trig - toml_12953 - 04-01-2022, 02:56 AM
RE: SOHCAHTOA, for arc-trig - Albert Chan - 04-02-2022 12:10 AM
RE: SOHCAHTOA, for arc-trig - Albert Chan - 04-02-2022, 09:59 AM
RE: SOHCAHTOA, for arc-trig - Albert Chan - 04-02-2022, 01:51 AM
RE: SOHCAHTOA, for arc-trig - Albert Chan - 04-06-2022, 08:46 PM
RE: SOHCAHTOA, for arc-trig - trojdor - 04-07-2022, 08:10 AM
RE: SOHCAHTOA, for arc-trig - Albert Chan - 04-09-2022, 01:07 PM
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