- #1
jwxie
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Homework Statement
cos(2 * arcsin(2x))
Use a triangle to simplify each expression. Where application, state the range of x's for which the simplification holds.
Homework Equations
cos(2t) = cos^2(t) - sin^2(t) = 1-2sin^2(t) = 2cos^2(t) - 1
The Attempt at a Solution
My attempt was the following
cos(2*arcsin(2x))
let arcsin(2x) = delta (or t)
so cos(2t) = double angle formula
cos2(t) = 1-2sin^2(t)
replace t, and by definition sin(arcsinx) = x
so i think i got 1-2*(2x)^2 = 1-8x^2
please verify for me
thank you