Block on Incline (2)

A block of mass M rests on an fixed incline plane of angle $$\theta$$. A horizontal force of magnitude Mg is applied on the block, If the coefficient of static friction of the incline be $$0.5$$ . For what ranges of $$\theta$$ will the block still remain at rest?

Note : The answer is of the form $$a\leq tan\theta\leq b$$ Find $$ab$$

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