Originally Posted by **dadon**

hi all,

How about do I go to answer the following rate of change question.

A ladder of length 10metres is placed with one end of the horizontal ground and the other end against a vertical wall. Given the ladder makes an angle $\displaystyle \theta $ with the horizontal then it slips vertically down the wall at rate of 2 metres/sec. Find the rate at which the angle $\displaystyle \theta $ is decreasing at the distant when $\displaystyle \theta = \pi/4$ radian.

To help I have attached a picture.

I know the rate has to be minus (-2m/sec) as it is decreasing.

Can someone please explain the process step by step as I am totally lost

Thanks