1. FYI
Chapter 1 test on Thursday. Chapter review available on line at Login (in most cases) is your 1st initial, last name 2014 ie. Jesse Dawes would be JDawes2014. In a few exceptions if this login doesn’t work put the whole 1st name, JesseDawes2014. Password: geometry1

2. Lines
Monday, August 25, 2014

3. Length of a straight line
To find the length of a line, subtract = 10 5 15
The line is 10 units long. 5
Again subtract.
5 – (-2) = = 7
This line is 7 u long. -2

4. Midpoint
To find the midpoint of a line segment, add the end points and divide by two, 5 10 15
= 20 / 2 = 10.
Halfway between 5 and 15 is 10

5. What is the line is slanted?
In the case of a slanted line find the distance between the components. (x1, y1) and (x2, y2)
-2, 6
4, -5
Begin with the distance formula:
√(x2 – x1)2 + (y2 – y1)2 = √n
√(4 – (-2))2 + ((-5) – 6)2
√ = √157

6. More simply put
Find the distance in the X direction and square it. 4-(-2) = 62 = 36 Find the distance in the Y direction and square it. -5 – 6 = -112 = 121 Sum and take the square root. √157 = 12.5
-2, 6
4, -5 c b 11 a 6
Remember this?
a2 + b2 = c2
= 157
√157 = 12.5
Distance formula.

7. Perimeter
The distance around a polygon is called the perimeter. For a rectangle the formula is: 2L + 2W = P; where L is the length, W is the width and P is the perimeter.
16 cm
10 cm
2(16) + 2(10) =
= 52 cm

8. Circumference
Circumference is like the perimeter, but it goes around the circle. The formula for circumference is: Diameter ∙ pi or dπ = C; where d is diameter, π is pi and C is circumference.
The radius (r) is half the diameter.
When the radius is the only thing given, multiply by 2.
4(2)π = 8π = u
In terms of pi. 3π
With pi approximated multiply (3.14)
3(3.14) = 9.42 in 3 d r 4

9. Area
To find the area of a rectangle multiply length x width. Don’t forget units are squared To find the area of a circle, square the radius and multiply by pi. 3
16 cm
10 cm
16 cm x 10 cm = 160 cm2
3 is diameter. r is ½ diameter.
Most accurate = ½(3)2π
Approximate = (1½)2(3.14)
= u2

10. Assignment
Workbook 1-7 p 29 and 1-8 p 33 on a separate sheet of paper. Be sure to show all work. If you use a calculator, write the problem out followed by the word “calculator” Ie.What is the perimeter of a rectangular pool that is 5 feet wide and 8 feet long? Answer: (2)(5) + (2)(8) = 640 ft2 calculator You could also say “mental math” Exception is when pi is left as a symbol.