The angles of depression of the top and the bottom of an 8 m tall building from the top of another multistoried…
CBSE Class 10 Maths PYQ · Applications of Trig · Double Triangle · 5 Marks · March 2025 · Standard
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625 Marks · March 2025 · Standard
The angles of depression of the top and the bottom of an $8$ m tall building from the top of another multistoried building are $30^\circ$ and $45^\circ$, respectively. Find the height of the multistoried building and the distance between the two buildings.
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Correct figure Here, CD represents the multistoried building. In right $\triangle DEA$ $\frac{DE}{AE} = \tan 30^\circ = \frac{1}{\sqrt{3}}$ $\Rightarrow AE = \sqrt{3} DE$ ----- (1) In right $\triangle DCB$ $\frac{DC}{BC} = \tan 45^\circ = 1$ $\Rightarrow BC = DC$ ----- (2) From figure, AE = BC $\therefore \sqrt{3} DE = DC$ $\Rightarrow \sqrt{3} (DC - 8) = DC$ $\Rightarrow DC = \frac{8\sqrt{3}}{\sqrt{3}-1}$ $= \frac{8\sqrt{3}}{\sqrt{3}-1} \times \frac{\sqrt{3}+1}{\sqrt{3}+1} = (12 + 4\sqrt{3})$ m From (2), BC = $(12 + 4\sqrt{3})$ m