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An insect crawls up a hemispherical surf...

An insect crawls up a hemispherical surface very slowly (see the figure). The coefficient of friction between the insect and the surface is 1/3. If the line joining the centre of the hemispherical surface to the insect makes an angle `alpha` with the vertical, the maximum possible value of `alpha` is given by

A

`cos alpha=3`

B

`tan alpha=3`

C

`sec alpha=3`

D

`"cosec" alpha=3`

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The correct Answer is:
A
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