Try it on paper first. A hint, the key idea and the worked solution are here when you need them.
A designer is planning the curved profile of a long roof. She places the wall at metre and measures along the ground in metres. The height of the roof above the ground is metres, and at the wall the height is metres, so when . The slope of the roof at distance is for . She sees that the factor is the derivative of , and that in the bottom is a standard form. She wants the equation of the roof, and then the height at metres and at metres. She also wants to know how high the roof can get. As becomes very large, the height tends to a limit, and no point of the roof is above that limit. Find the heights at and at , and the limit of the height. Give each height in metres to four decimal places.
Put and , so that . Replace every , integrate in , then return to .
Have you tried it?
Work it out on paper first. It is fine to get stuck or make a mistake: that is how we learn. When you are ready, go through the solution one step at a time, and check each step against your own.
Given. and .
Plan. Substitute , integrate, use , then evaluate and take the limit.
Step 1. Substitute. With we have . The integral is , so .
Step 2. The constant. At , and . So and .
Step 3. The heights. At , and . At , and .
Step 4. The limit. As , , and .
Answer: , and .
Check. The slope is always positive, so the roof keeps rising. It rises more and more slowly, which fits a limit.
Log in to join the discussion.
Loading…
With Standard, you also open 12 more problems, 2 Python labs and 1 extra course. Everything you have used here stays free, always.