# word problem dont know were to start

• Oct 17th 2008, 04:20 AM
Tweety
word problem dont know were to start
Hi, I am really stuck on this question ,

fig.19.2 shows a template whose area is 50 square centimetres. find the total length of the template.

I have drawn the image on paint and have attached it, but its not a very good drawing. sorry if it does not make much sense to you!

I would be able to work this out if it was just the square but because there’s also this semi-circle shape attached to the square i don't really know how to calculate the length of it.
• Oct 17th 2008, 05:24 AM
Peritus
$\displaystyle \begin{gathered} Area_{template} = x^2 + \frac{{\pi \left( {\frac{x} {2}} \right)^2 }} {2} = 50 \\ Length_{template} = 3x + \frac{{\pi x}} {2} \hfill \\ \end{gathered}$

good luck...
• Oct 17th 2008, 05:43 AM
Tweety
Quote:

Originally Posted by Peritus
$\displaystyle \begin{gathered} Area_{template} = x^2 + \pi \left( {\frac{x} {2}} \right)^2 = 50 \hfill \\ Length_{template} = 3x + \frac{{\pi x}} {2} \hfill \\ \end{gathered}$

good luck...

I don't really understand how you got to your final 2 equations(Worried) could you please explain it step my step? please

thanks!

p.s. what do I do with the length of the square? which is 6cm? where am I suppose to use that?
• Oct 17th 2008, 05:55 AM
Peritus
let us denote the side of the square by x.
The area of the square is $\displaystyle x^2$.
From your drawing I understand that there's a half circle on the rightmost side of the square, so basically the diameter of the circle equals the side of the square (x). We know that the area of a circle is:
$\displaystyle \pi r^2$

where r is the radius of the circle (the diameter is twice the radius).
So we can express the area of the half circle using x, like so:

$\displaystyle \frac{{\pi \left( {\frac{x} {2}} \right)^2 }} {2}$

the area of the template is the sum of the square area and the half circle area, and that's how we get the first equation, I hope that you can figure out the second equation now.
• Oct 17th 2008, 08:15 AM
Tweety
I kind of understand the first equation, but i am still not sure how to calculate the total length of the template, would I just add all the sides up together?

and isn't the area of the square 36cm^2 ?
• Oct 17th 2008, 10:39 AM
Tweety
can someone please show me how to calculate the total length , please. maths is not my best subject (Doh)