Join IDNLearn.com and start getting the answers you've been searching for. Find reliable solutions to your questions quickly and easily with help from our experienced experts.

SCALCET8 3.9.004.MI. The length of a rectangle is increasing at a rate of 7 cm/s and its width is increasing at a rate of 8 cm/s. When the length is 15 cm and the width is 7 cm, how fast is the area of the rectangle increasing

Sagot :

Answer:

The area of the rectangle is increasing at a rate of 169 cm²/s

Step-by-step explanation:

Given;

increase in the length of the rectangle, [tex]\frac{dL}{dt} = 7 \ cm/s[/tex]

increase in the width of the rectangle, [tex]\frac{dW}{dt} = 8 \ cm/s[/tex]

length, L = 15 cm

width, W = 7 cm

The increase in Area is calculated as;

[tex]Area = Length \times Width\\\\A = LW\\\\\frac{dA}{dt} = L(\frac{dW}{dt} )\ + \ W(\frac{dL}{dt} )\\\\\frac{dA}{dt} = 15 \ cm(8\ \frac{ cm}{s} ) \ + \ 7 \ cm(7\ \frac{ cm}{s} ) \\\\\frac{dA}{dt} = 120 \ cm^2/s \ + \ 49 \ cm^2/s\\\\\frac{dA}{dt} = 169 \ cm^2/s[/tex]

Therefore, the area of the rectangle is increasing at a rate of 169 cm²/s