Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Homework Help: Math 31 Rates of change

  1. Apr 13, 2005 #1
    I need help with the question: The heighth of an equilateral triangle is increasing at a rate of 3cm/min. How fast is the area changing when h is 5cm?
     
  2. jcsd
  3. Apr 13, 2005 #2
    The area of a triangle is A= 1/2*bh

    You know dh/dt = 3cm/min


    Try manipulating the above equations to an appropriate form where you can find the area as a function of height, and inhernetly its rate of change.
     
  4. Apr 14, 2005 #3

    HallsofIvy

    User Avatar
    Science Advisor

    Write the equation, which whozum gave you, A= (1/2)bh, Use a relation between b and h that is true for all equilateral triangles (divide the triangle into two right triangles and use the Pythagorean theorem) to write A as a function of h only.
    Finally, differentiate with respect to t to get a relation between dA/dt and dh/dt.
     
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook