Geometry

1
Geometry
You need to know r radius d diameter h
height b base W width L length and
( ) mean multiplication
2
Area of a Rectangle

• Formula A L(W)

Example
21mm
Solution
L 21 W 5 A 21 (5) 105 mm squared
5mm
5mm
21mm
3
Area of a Triangle
Formula A 1/2 b h
Solution b 25, 1/2 b 12.5 h 5 A 12.5
(5) 62.5cm squared
Example
9cm
5cm
25cm
4
Area of a Circle
Formula A 3.14(r) squared, or A 3.14(d)
squared divided by 4
Solution A 3.14(9.9)(9.9) 3.14(98.01)
307.75 ft squared
9.9ft
5
Volume of a Cylinder
Formula V 3.14( r)(r)(h)
Solution V 3.14(8)(8)(5) 3.14(64)(5)
3.14(320) 1004.8 m cubed
8m
5m
6
Volume of a Cone
Formula V 1/3(h)(3.14)( r )( r )
Solution V (1/3)(5)(3.14)(2)(2)
(5/3)(3.14)(2)(2) (5.23)(2)(2) (10.46)(2)
20.92 m cubed
h 5 m r 2 m
7
Volume of a Sphere
Formula V 4/3(3.14)( r )( r )( r )
Solution V (1.33)(3.14)(6)(6)(6)
(4.19)(6)(6)(6) (25.12)(6)(6) (150.72)(6)
904.32 cm cubed
6cm
8
Surface Area of a Cylinder
Formula A 4(3.14)( r )( r )
Solution A 4(3.14)(12)(12) 12.56(12)(12)
150.72(12) 1808.64cm squared
12cm
9
Surface Area of a Rectangular Prism
Solution A 2(17)(6) 2(17)(9) 2(6)(9)
34(6) 2(17)(9) 2(6)(9) 204 2(17)(9)
2(6)(9) 204 34(9) 2(6)(9) 204 306
2(6)(9) 204 306 12(9) 204 306 108
510 108 618 cm squared
Formula A 2 lw 2 lh 2 wh
l 17cm
w 6cm
h 9cm
10
Perimeter of a Rectangle
Formula P 2 l 2 w or 2 (lW)
6cm
Solution P 2(6) 2(5) 12 10 22cm
Solution P 2(65) 2 (11) 22cm
5cm
11
Circumference of a Circle
Formula C 2(3.14)(r) or 3.14(d)
Solution C 2(3.14)( r ) 2(3.14)(3.5)
6.28(3.5) 21.98 in
Solution 3.14(d) 3.14(7) 21.98 in
7 in
12
The End