Find the exact solution to the equation without a calculator.
-$\cos ^ { - 1 } ( \cos x ) = 1.8$
A) $0.9$
B) $3.6$
C) $1.8$
D) 0

Question

Quizplus · Accepted Answer

The equation $\cos^{-1}(\cos x) = 1.8$ essentially simplifies to $x = 1.8$ because the cosine inverse function and the cosine function are inverse operations of each other, which cancel out when applied sequentially, given that $1.8$ (in radians) falls within the principal range for $\cos^{-1}$ which is $[0, \pi]$.

Find the Exact Solution to the Equation Without a Calculator cos⁡−1(cos⁡x)=1.8\cos ^ { - 1 } ( \cos x ) = 1.8cos−1(cosx)=1.8

Find the Exact Solution to the Equation Without a Calculator $\cos ^ { - 1 } ( \cos x ) = 1.8$