How do you solve cos^2theta=1?

1 Answer
Acquaintance
Nov 25, 2016

First take the square root of both sides.

sqrt(cos^2theta) = sqrt1

Simplify, and don't forget the +-!

costheta = +-1

Now think back to the unit circle and find the values where cos (x-values) is equal to +-1.

theta = 0, pi

Those are the answers in the range from 0 to 2pi (which is one unit circle), but if you want all solutions (like every single one), then it would look like:

theta = 2pin, pi + 2pin

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