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A tree is broken by the wind. The top of that tree struck the ground at an angleof 30°& at a distance of 30 m from the root. Find the height of the whole tree. |
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Answer» The tree breaks at point D ∴ seg AD is the broken part of tree which then takes the position of DC ∴ AD = DC m∠ DCB = 30º BC = 30 m In right angled ∆DBC, tan 30º = side opposite to angle 30º/adjacent side of 30º ∴ tan 30º = BD/BC ∴ 1/√3 = BD/30 ∴ BD = 30/√3 ∴ BD = (30/√3)×(√3/√3) ∴ BD = 10√3 m cos 300 = adjacent side of angle 300/Hypotenuse ∴ cos 300 = BC/DC ∴ cos 300 = 30/DC ∴ √3/2 = 30/DC ∴ DC = (30×2)/√3 ∴ DC = (60/√3)×(√3/√3) ∴ DC = 20√3 m AD = DC = 20 √3 m AB = AD + DB [∵ A - D - B] ∴ AB = 20 3 + 10 3 ∴ AB = 30 3 m ∴ AB = 30 × 1.73 ∴ AB = 51.9 m ∴ The height of tree is 51.9 m. Hit like if you find it useful! |
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