Mathematics

Range of function $$f ( x ) = \cos ( k \sin x )$$ is [-1 , 1 ] then the least positive integral value of k will be


ANSWER

1


SOLUTION
$$\cos(k \sin x)\in [-1,1]$$
so $$k \sin x=[-\pi,\pi]$$
for $$x\in R$$   $$\sin x \in [-1,1]$$
$$[-k,k]=[-\pi,\pi]$$
so least integral
value is $$1$$
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Single Correct Medium Published on 17th 09, 2020
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