# Trapezium rule

• Sep 9th 2011, 11:50 AM
celtic1234
Trapezium rule
Hi all,
I am currently studying the trapezium rule in Integration.
Can you tell when when the question asks for "an approximate" value of the integral-how many decimal places is appropriate?
thanks
John
• Sep 9th 2011, 12:43 PM
e^(i*pi)
Re: Trapezium rule
Quote:

Originally Posted by celtic1234
Hi all,
I am currently studying the trapezium rule in Integration.
Can you tell when when the question asks for "an approximate" value of the integral-how many decimal places is appropriate?
thanks
John

When a question says "approximate value" it usually means there is no analytical solution so a numerical approach is needed of which the trapezium rule is one such approach. Since you're only using numbers instead of letters you can never get the exact value.

It's the same principle to why $\displaystyle 3.1415926535 8979323846 2643383279 5028841971$ is only an approximation of $\displaystyle \pi$

For your question 3 significant figures or 2 decimal places should be fine but really you're meant to round to your least accurate number in working (ie: 4 is only 1sf) but your teacher will usually tell you what they expect in rounding accuracy.
• Sep 9th 2011, 10:30 PM
celtic1234
Re: Trapezium rule
thanks very much!
John