MHT CET20228 Aug 2022Evening ShiftMathematicsApplication of DerivativesActual
Let A D and B C be two vertical poles at A and B respectively on a horizontal ground. If A D=8 ~m , B C=11 ~m and A B=10 ~m , then the distance (in meters) of point M on A B from the point A such that M D^2+M C^2 is minimum, is
Options
- A8
- B5
- C4
- D7
Correct answer
B. 5
Step-by-step solution
aligned & f(x)=M D^2+M C^2 & f(x)=x^2+8^2+(10-x)^2+11^2 & f^ (x)=2 x-2(10-x) & f^ (x)=4 x-20 & for f(x) to be minimum x=5 aligned