idk how to solve this really need help

Question

A ladder l = 21 ft long is leaning against the
wall of a house. The base of the ladder is
pulled away from the wall at a rate of 2.1 ft/s,
and the top slides down the wall. Consider
the triangle formed by the side of the house,
the ladder, and the ground.

What is the area when the base of the
ladder is 7.9 ft from the wall?

Answer 1

Hey, they have described a picture, so draw a version of it. You'll have a right triangle with hypotenuse c=21 ft and horizontal leg a=7.9 ft.  Use Pythagorean theorem to calculate the length of the other leg b, which in fact is the height of the triangle.

 

The area that is desired is obtained by the formula Area = (½)ab where a and b are the lengths of the legs, i.e. base times height over two.