The function is .

Apply derivative on each side with respect to t .

Quotient rule of derivatives : .

Power rule of derivatives: .

To find the critical numbers of , equate  to zero.

 is in the region .

Critical points in the given region is .

To find the absolute extreme of function in given region  , sketch the function.

Critical point  is minimum point over the interval .

Left end point  is maximum point over the interval .

Right end point  is maximum point over the interval .

Minimum point is  .

Maximum point are  and .