How do you solve the equation on the interval [0,2pi) for #cos^2 theta - cos theta - 2 = 0 #?
1 Answer
Jul 22, 2016
Explanation:
f(t) = cos^2 t - cos t - 2 = 0
This is a quadratic equation for cos t.
Since a - b + c = 0, use shortcut. Two real roots: cos t = - 1 and
cos t = -c/a = 2
a. cos t = - 1 -->
b. cos t = 2 (rejected since > 1)
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