We become what we think about most of the time, and that’s the strangest secret. – **Earl Nightingale**

# Part - 9 Lecture - 11 Chapter 6 Application of Derivatives

**Topics discussed in this lecture:**

In this lecture I am discussing word problems in chapter 6 Applications of derivatives based on Local Maxima and Local Minima.

NCERT EXERCISE 6.5 |

**Question discussed in this lecture**

**Question 20. **Show that the right circular cylinder of given surface and maximum volume is such that its height is equal to the diameter of the base.

**Question 21.** Of all the closed cylindrical cans (right circular), of a given volume of 100 cubic centimetres, find the dimensions of the can which has the minimum surface area?

**Question 22.** A wire of length 28 m is to be cut into two pieces. One of the pieces is to be made into a square and the other into a circle. What should be the length of the two pieces so that the combined area of the square and the circle is minimum?