Porisma

Extend an inverse-cosine piece periodically and solve a threshold

It is given that

f(x)={cos⁡−1xfor 0≤x<1,π2x−π2for 1≤x<2f(x)=\begin{cases}\cos^{-1}x&\text{for }0\leq x<1,\\\dfrac\pi2x-\dfrac\pi2&\text{for }1\leq x<2\end{cases}

and that f(x)=f(x+2)f(x)=f(x+2) for all real values of xx.

(i) Sketch the graph given by y=f(x)y=f(x) for −3≤x≤4-3\leq x\leq4. [3]

(ii) For 0≤x≤40\leq x\leq4, solve the inequality f(x)>π3f(x)>\dfrac\pi3, giving your answer in the exact form. [3]

[2015/VJC/JC1MYE/2]

CJC · Review Problems · Question 8

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