# apply complex mathematical concepts to building and constructions principle

• Jan 6th 2010, 01:12 AM
seran
apply complex mathematical concepts to building and constructions principle
Hi, i urgently need help with this subject, i need to complete it for a course i am wanting to enrol in, but maths wasn't for me, now i am stuck. i need help with this question,

Find the area of the triangle with the lengths 2.87 m, 3.69 m and 4.58 m
565 mm, 823 mm and 1.08 m

i have no idea how to do this,

• Jan 6th 2010, 02:09 AM
Prove It
Quote:

Originally Posted by seran
Hi, i urgently need help with this subject, i need to complete it for a course i am wanting to enrol in, but maths wasn't for me, now i am stuck. i need help with this question,

Find the area of the triangle with the lengths 2.87 m, 3.69 m and 4.58 m
565 mm, 823 mm and 1.08 m

i have no idea how to do this,

Use Heron's Formula.

If $a, b, c$ are the sides of the triangle, let $s$ be the semi-perimeter. I.e. $s = \frac{a + b + c}{2}$.

Then the Area is

$A = \sqrt{s(s - a)(s - b)(s - c)}$.
• Jan 6th 2010, 11:55 PM
seran
sorry ur going to think im pretty stupid, i did say im hopless in mtahs, but where did u get the 2 and s from???

you've lost me sorry
• Jan 7th 2010, 12:29 AM
Prove It
Follow the instructions I gave you.

Call the three sides of your triangle $a, b, c$.

Then work out the semiperimeter:

$s = \frac{a + b + c}{2}$.

Then work out the Area

$A = \sqrt{s(s - a)(s - b)(s - c)}$.
• Jan 7th 2010, 07:17 AM
Soroban
Hello, seran!

If you can't handle Heron's Formula,
. . then you must know some Trigonometry.

Quote:

Find the area of the triangle with the lengths 2.87 m, 3.69 m and 4.58 m

565 mm, 823 mm and 1.08 m .
What are these?
We have a triangle:
Code:

            C             o           *  *       b  *    *  a         *        *         *          *       *              *     A *  *  *  *  *  *  * B               c
We are given: . $\begin{array}{ccc}a &=& 2.87 \\ b &=& 3.69 \\ c &=& 4.58 \end{array}$

We can find angle $A$ with: . $\cos A \:=\:\frac{b^2+c^2 - a^2}{2bc}$

Then the area is: . $\tfrac{1}{2}bc\sin A$

If all this is meaningless to you,
and you're really "hopless in math",
. . . . just skip the problem.

• Jan 7th 2010, 07:47 AM
Hi seran,

If you need this subject for a course you want to enroll in,
why is this topic important for the course ?

Will you have difficulty on the course without it ?
Try the question, you might be surprised how easy it can get.

As Soroban showed,

If you have the 3 sides of a triangle,
you can find any angle using the Law of Cosines, or Cosine Rule

Then,
you can find the area of a triangle if you have all 3 dimensions at any of the 3 corners,
using the triangle area formula, for a triangle for which you are not given the perpendicular height and base.
• Jan 18th 2010, 04:40 PM
seran
I want to study architecture and one of the pre-req is that i have to have completed maths in year 12, which i never did, so the course i will be doing am assuming won't involve algebra etc, just measure etc. i haven't done maths since 1993, thats 17 years. so really nothing is sinking in and is getting really depresed cause i feel so stupid. thanks all for your helps.(Speechless)
• Jan 18th 2010, 04:44 PM
seran
Hi, thank you all, ooo i feel stupid, no i don't know trig, like i mentioned i did maths about 17 years ago, and really never paid attention to the teacher because maths was never my best friend. so i didnt take it up in year 12 either. Now i want to study from home architecture and one of the pre-req is that i have to have completed maths in year 12. Or to do this subject, i think i need a private tutor. :(
• Jan 18th 2010, 04:46 PM
VonNemo19
Quote:

Originally Posted by seran
I want to study architecture and one of the pre-req is that i have to have completed maths in year 12, which i never did, so the course i will be doing am assuming won't involve algebra etc, just measure etc. i haven't done maths since 1993, thats 17 years. so really nothing is sinking in and is getting really depresed cause i feel so stupid. thanks all for your helps.(Speechless)

You're in for a suprise! You're gonna need a lot of math there, buddy!

Check it out.

Architecture Degree Program Requirements
• Jan 18th 2010, 04:49 PM
seran
ooo, know i feel even worse, gota get a tutor, thnax for that, :)