Hey everyone,(adsbygoogle = window.adsbygoogle || []).push({});

We've been covering tangents and derivatives etc in class recently but there is a question on the assignment that we've been given that i don't know how to do.

The question is:

"A quadratic equation can be fitted to any three points on a cartesian plane. The model for such an equation in y=ax + bx+ c. By substitution three seperate points (The first, middle and last data points) derive the equation of the Quadratic function that models the data."

The situation is a cup of hot coffee is left to cool over a 50 minute period and we have been given this table of values:

mins : Degrees Celcius

0 :83

5 :76.5

8 :70.5

11:65

15:61

18:57.5

24:52.5

35: 51

30:47.5

34:45

38:43

42:41

45:39.5

50:38

From there i have plotted the time vs. temp graph and attached 3 tangents to points time (t) = 0, t = 25 & t = 50.

at t=0 the Rate of Change or gradient was -1.85Degrees/min

at t=25, the ROC or Gradient was -0.92degrees/min

at t=50, the ROC or Gradient was -0.13degrees/min

I'm not asking for you to do this for me, im just asking for the path i need to take or an idea of what i need to do...

Thanks everyone,

Chris

**Physics Forums | Science Articles, Homework Help, Discussion**

Join Physics Forums Today!

The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

# Homework Help: Finding the Quadratic of a Graph using Tangents

**Physics Forums | Science Articles, Homework Help, Discussion**