Page 101 - How To Solve Word Problems In Calculus
P. 101
1600 + 400π − 800 − 200π
=
(4 + π) 2
800 + 200π
=
(4 + π) 2
200(4 + π)
=
(4 + π) 2
200 2
= ≈ 28.005 ft
4 + π
EXAMPLE 8
Find the rectangle of largest area that can be inscribed in an
equilateral triangle of side 20.
Solution
Step1
It is convenient to let the width of the rectangle be 2x. Its
height is y.
20 h
y
x x 10 − x
10 10
Step2
The area of the rectangle is 2xy.
Step3
By the theorem of Pythagoras, the altitude h of the equi-
lateral triangle can be easily determined:
88
