If [theta] is an acute angle with sin[theta]=3/5, find the exact value of cos2[theta].

This is the last one I am stumped on.

Call theta = t for simplicity.

cos^2(t) = 1 - 2*sin^2(t) = 1 - 2*(3/5)^2 = 1 - 2*9/25

= 1 - 18/25 = 7/25

-Dan

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"I must not fear. Fear is the mind killer. Fear is the little death that brings total obliteration. I will face my fear. I will permit it to pass over me and through me. And when it has gone I will turn the inner eye to see its path. Where the fear has gone there will be nothing. Only I will remain." - The Litany Against Fear, "Dune" by Frank Herbert

You may use the formula to solve the questions related to this as

cos 2(theta)=cos^2 (theta) - sin^2 (theta)
= 1- 2*sin^2 (theta)
= 2*cos^2 (theta) - 1

These are the formulas to solve the problem