# Math Help - Equable shapes/Formulae

1. ## Equable shapes/Formulae

Ok I have this Maths courseowrk that has to be in tomorow and i've only done the simplest parts and now i need help coz my teacher will kill me if i dont kill myself first!

Anyway, so, i need to know the formula for the area/volume of these shapes in x/y form:
Paralellogram
Cylinder
Regular pentagon
Right angled triangle (shortest lengths x and y)
Isosceles triangle
Square based pyramid
Cone

And then i need help with how to work out the equation e.g:

Cirlce - Area = Pi*r²
Circumference = 2*Pi*r

2*Pi*r = Pi*r² (/r)(/Pi)
r = 2

Rectangle - Perimeter = 2x + 2y
Area = xy

xy = 2x + 2y (-2x)
xy - 2x = 2y
x (y - 2) = 2y (/ (y - 2))
x = 2y / y - 2

If anyone can help it would be amazing!!!
Thanks x

2. For formulae, Area and Volume Formula for geometrical figures.

Specify your problem which you don’t get.

3. I don't know how to work through the equations eg:

So looking at the site i've been given i need to do -

Parallelogram-
2x + 2y = x * h

I have a worksheet from my teacher that tells me the answers but I dont know how to get to the answer which is x = 2y / (h - 2)

4. Originally Posted by mememe_fun91
I don't know how to work through the equations eg:

So looking at the site i've been given i need to do -

Parallelogram-
2x + 2y = x * h

I have a worksheet from my teacher that tells me the answers but I dont know how to get to the answer which is x = 2y / (h - 2)
$2x + 2y = xh$

$-xh + 2x + 2y = -xh + xh$

$-xh + 2x + 2y = 0$

$-xh + 2x + 2y - 2y = 0 - 2y$

$-xh + 2x = -2y$

$x(-h + 2) = -2y$

$\frac{1}{-h + 2} \cdot x(-h + 2) = \frac{1}{-h + 2} \cdot (-2y)$

$x = \frac{-2y}{-h + 2}$

$x = \frac{-2y}{-h + 2} \cdot \frac{-1}{-1}$

$x = \frac{2y}{h - 2}$

-Dan