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Deepak Four-in-ne Revision Model Test PapersA straight highway leads to the foot of a tower. A man standing at the top of the tower observes a car atan angle of depression of 30째, which is approaching the foot of theseconds later, the angle of depression of the car is found to be 60째. Find the time taken by the car toreach the foot of the tower from the point..tower with a uniform speed. Six |
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Answer» Let the distance traveled by the car in 6seconds=AB=X metresHeight of the tower CD=h metresThe remaining distance to be traveled by the car BC =d metresAC =AB+BC=x+d metresANGLE PDA=ANGLE DAC=30ANGLE PDB=ANGLE DB*C=60 TRIANGLE BCD TAN60=CD/BC=root3=h/dh=root3dTRIANGLE ACD TAN30=CD/AC1/root3=h/(x+d)h=(x+d)/root3(x+d)/root3=root3dx+d=3dx=2dd=x/2Time taken to travel x metres =6secondsTime taken to travel the distance of D metres i. e., x/2=6/2=3seconds |
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