# A projectile's launch speed is five times its speed at maximum height.Find launch angle.How do I find this?

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Ananda Dasgupta
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Mar 11, 2018

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If the angle of projection is

At the topmost point of the path, the projectile's vertical velocity component vanishes - and thus its velocity at that point is exactly horizontal, and its magnitude is

Thus $u = 5u cos alpha implies cos alpha = 1/5#

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