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The range of a projectile when launched at angle `theta` is same as when launched at angle `2theta`. What is the value of `theta` ?A. `15^(@)`B. `30^(@)`C. `45^(@)`D. `60^(@)` |
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Answer» Correct Answer - B Range of projectile launched at an angle `theta` is same as the range of projectile launched at angle `2theta`. `rArr (u^(2)sin2 theta(2theta))/(g) = (u^(2) sin 2 theta)/(g)` `rArr sin 2(2theta) = sin 2theta` `rArr 2 sin 2 theta cos 2 theta = 2 sin theta cos theta` `4 sin theta cos theta cos 2 theta = 2 sin theta cos theta` `rArr 4 cos 2 theta = 2 rArr cos2 theta = (1)/(2)` `rArr cos 2theta = cos 60^(@)` `rArr 2 theta = 60^(@)` `rArr theta = 30^(@)` |
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