Thursday, March 25, 2010

Deniel's surface area growing post

Okay guys here is my surface area growing post about right rectangular prism, right triangles, and cylinders

Here is my first surface area question:
Okay here is what I did:

front:
13.5 cm x 18.5cm =area 13.5 x 18.5= 249.75cm x 2 = 499.5cm
side:
5 cm x 13.5cm =area 13.5 x 5= 67.5cm x 2 = 135cm
length:
18.5 cm x 5cm =area 18.5 x 5= 92.5cm x 2= 185cm

499.5+135+185= 819.5
Area= 819.5cm

Here is my second question:
Okay so here's what I did:

A= l x w A= (b x h) / 2
A= 9 x 3 A=(3 x 2.6) / 2
A= 27 The area on one rectangle is 27m A=7.8 / 2
A=3.9 and its the area of one triangle

Surface Area= (3 x rectangle) + (2 x area of triangle)
= (3 x 27) + (2 x 3.9)
= 81 + 7.8
= 88.8
So the surface area is 88.8 centimetre squared.

Here's my third question:
Here's what I did:
Determine the radius of each circle:
7.5 / 2 = 3.75 so 3.75 is the radius of each circle

Find the area of the circle
A=π x r2
A=3.14 x 3.75 x 2
A= 44.15625 so the area of one circle is 44.15625 x 2 = 88.3125 for both circles.

Find the area of the rectangle using the circumference of the circle.
A= l x w
A=(π × d) × w
A= 3.14 × 7.5 × 11
A= 259.05
The area of the rectangle is approximately 259.05 cm2.

Calculate the total surface area.
Surface area = 88.3125 + 259.05
= 347.3625
The total surface area is approximately 347.36 cm2

So here is my surface area growing post :)


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