Speed of student A is 180 ft/min
Speed of student B is 120 ft/min
Relative speed=(120+180)=300 ft/min
Distance between them is 2420 ft
Time taken for them to meet will be:
time=distance/speed
=(2420-20)/300
=8 min
It is valid.
The three angles must add up to 180. So, if one is more than 90, the other two have to be less than 90.
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SR = 450
<span>S = 450/R </span>
<span>(S - 3)(R + 5) = 450 </span>
<span>(450/R - 3)(R + 5) = 450 </span>
<span>(450 - 3R)(R + 5) = 450R </span>
<span>450R + 2250 - 3R^2 - 15R = 450R </span>
<span>3R^2 + 15R - 2250 = 0 </span>
<span>R^2 + 5R - 750 = 0 </span>
<span>R^2 + 30R - 25R - 750 = 0 </span>
<span>R(R + 30) - 25(R + 30) = 0 </span>
<span>(R + 30)(R - 25) = 0 </span>
<span>R ∈ {-30,25}
</span>
<span>Only positive numbers make sense in this context, therefore R = 25.</span>