question_answer

In the interval \[\left[ 0,\frac{\pi }{2} \right]\], the equation \[{{\cos }^{2}}x-\cos \,x-x=0\] has

A)  no solution                              

B)  exactly one solution

C)  exactly two solutions                     

D)  more than two solutions

Correct Answer: B

Solution :

 \[\sqrt{2}\,mv\]\[\sqrt{2}\,mv'=(2m)\,v\] From graph there is only solution.