## Saturday, March 10, 2012

### Shera's Surface Area and Volume Post

Rectangular Prism

Top:
Length - 5m
Width - 10m

A = l x w
A = 5 x 10
A = 50m²

Front:
Length - 6m
Width - 10m

A = l x w
A = 6 x 10
A = 60m²

Side:
Length - 5m
Width - 6m

A = l x w
A = 5 x 6
A = 30m²

TSA = 2 (T+F+S)
= 2 (50+60+30)
= 2 (140)
= 280m²

Triangular Prism

Rectangle 1
Length - 8cm
Width - 5cm

A = l x w
A = 8 x 5
A = 40cm²

Rectangle 2
Length - 10cm
Width - 5cm

A = l x w
A = 10 x 5
A = 50cm²

Rectangle 3
Length - 9cm
Width - 5cm

A = l x w
A = 9 x 5
A = 45cm²

Triangle
A = b x h / 2
A = 8 x 9 / 2
A = 72 / 2
A = 36cm²

TSA = 40 + 50 + 45 + 36 + 36
= 207cm²

Cylinder

r = d / 2
r = 8mm / 2
r = 4mm

c = πd
c=3.14 x 8
c = 25.12

L x W
25.12 x 12 = 301.44

Area of a Circle:

AO = πr²
AO = 3.14 x 4 x 4
AO = 50.24

TSA = Rectangle + Circle + Circle
= 301.44 + 50.24 + 50.24
= 401.92mm²

VOLUME
v = (b x h / 2) x h
v = (3 x 5 / 2) x 8.5
v = (15 / 2) x 8.5
v = 7.5 x 8.5
v = 63.75m 3
v = l . w . h
v = 20 x 8 x 16
v = 2560cm 3
v = (b x h / 2) x 6.5
v = (4 x 8 / 2) x 6.5
v = (32 / 2) x 6.5
v = 16 x 6.5
v = 104cm 3
104 / 8 = 13
13 x 3 = 39cm 3
r = d / 2
r = 12 / 2
r = 6cm
v = πr2 x h
v = 3.14 x 6 x 6 x 15
v = 1695.6cm 3