# Areas and Perimeters.

• Mar 29th 2009, 10:15 PM
suckatmaths
Areas and Perimeters.
I have this assignment at school to do with Areas and Perimeters. This is the final question, and I am totally stuck.

b) Find x if the total area is to be 1000m2

c) find the cost of the outer border given that materials cost $12.75 per metre. Diagram: ImageShack - Image Hosting :: picture541.jpg Is anyone able to help me? Oh yes, if it helps, this is the expression: A = x2 (1 + PI/2) m2 • Mar 29th 2009, 10:24 PM earboth Quote: Originally Posted by suckatmaths I have this assignment at school to do with Areas and Perimeters. This is the final question, and I am totally stuck. b) Find x if the total area is to be 1000m2 c) find the cost of the outer border given that materials cost$12.75 per metre.

Diagram:

ImageShack - Image Hosting :: picture541.jpg

Is anyone able to help me?

Oh yes, if it helps, this is the expression:

A = x2 (1 + PI/2) m2

1. The complete area consists of a square with side length x and two complete circles with radius $\displaystyle r = \frac x2$. Therefore solve for x:

$\displaystyle 1000 = x^2 + 2\cdot \pi\cdot \left(\dfrac x2\right)^2$

2. The perimeter of the area is the circumference of two circles with radius $\displaystyle r = \frac x2$. Therefore the costs of the border are

$\displaystyle c = \$12.75 \cdot 2 \cdot 2\pi\cdot \frac x2\$

Use the value of x from #1 to solve #2.