Question : A tower is broken at a point P above the ground. The top of the tower makes an angle of $60^\circ$ with the ground at Q. From another point R on the opposite side Q angle of elevation of point P is $30^\circ$. If QR = 180 m, what is the total height (in meters) of the tower?
Option 1: $90$
Option 2: $45\sqrt{3}$
Option 3: $45(\sqrt{3}+1)$
Option 4: $45(\sqrt{3}+2)$
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Correct Answer: $45(\sqrt{3}+2)$
Solution : Let OP = $h$ m In $\triangle$OPQ, $\tan60°=\frac{h}{OQ}$ ⇒ $OQ=\frac{h}{\sqrt3}$ ------------------(equation 1) In $\triangle$OPR, $\tan30^\circ=\frac{h}{OR}$ ⇒ $OR=h\sqrt3$ ----------------------(equation 2) According to the question, $h\sqrt3+\frac{h}{\sqrt3}=180$ ⇒ $3h+h=180\sqrt3$ ⇒ $h=\frac{180\sqrt3}{4}$ ⇒ $h=45\sqrt3$ m Now, in $\triangle$OPQ, $\sin60^\circ=\frac{h}{PQ}$ ⇒ $PQ=45\sqrt3×\frac{2}{\sqrt3}$ ⇒ PQ = 90 m So, the total height of the tower = $(45\sqrt3+90)=45(\sqrt3+2)$ m Hence, the correct answer is $45(\sqrt3+2)$ m.
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Question : In $\triangle P Q R, S$ is a point on the side QR such that $\angle Q P S=\frac{1}{2} \angle P S R, \angle Q P R=78^{\circ}$ and $\angle P R S=44^{\circ}$. What is the measure of $\angle PSQ$?
Option 1: 68$^{\circ}$
Option 2: 56$^{\circ}$
Option 3: 58$^{\circ}$
Option 4: 64$^{\circ}$
Question : $\triangle PQR$ is right-angled at $Q$. The length of $PQ$ is 5 cm and $\angle P R Q=30^{\circ}$. Determine the length of the side $QR$.
Option 1: $5 \sqrt{3}~cm$
Option 2: $3 \sqrt{3}~cm$
Option 3: $\frac{1}{\sqrt{3}}~cm$
Option 4: $\frac{5}{\sqrt{3}}~cm$
Question : The angle of elevation of the top of a tower from the top of a building whose height is 680 m is $45^{\circ}$ and the angle of elevation of the top of the same tower from the foot of the same building is $60^{\circ}$. What is the height (in m) of the tower?
Option 1: $340(3 + \sqrt3)$
Option 2: $310(3 - \sqrt3)$
Option 3: $310(3 + \sqrt3)$
Option 4: $340(3 - \sqrt3)$
Question : The angle of elevation of an aeroplane from a point on the ground is 45°. After flying for 15 seconds, the elevation changes to 30°. If the aeroplane is flying at a height of 2500 metres, then the speed of the aeroplane in km/h is:
Option 1: $600$
Option 2: $600(\sqrt{3}+1)$
Option 3: $600\sqrt{3}$
Option 4: $600(\sqrt{3}–1)$
Question : From point P on the level ground, the angle of elevation to the top of the tower is 30°. If the tower is 100 metres high, the distance of point P from the foot of the tower is: (Take $\sqrt{3}$ = 1.73)
Option 1: 149 m
Option 2: 156 m
Option 3: 173 m
Option 4: 188 m
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