Friday, December 9, 2011

Math Skills 12-6 Compass and clock

Degrees around a compass circle, clockwise from 12 o'clock North

12:00     0 degrees    0/8   north
1:30      45 degrees   1/8   northeast
3:00      90 degrees   1/4   east
4:30     135 degrees  3/8   southeast
6:00     180 degrees  1/2   south
7:30     225 degrees  5/8   southwest
9:00     270 degrees  3/4   west
10:30   315 degrees  7/8   northwest
12:00   360 degrees  8/8   north


Degrees around a clock circle, clockwise from 12 o'clock

12:00     0 degrees    0/8   midnight or noon
1:00      30 degrees   1/12  
2:00      60 degrees   1/6 
3:00      90 degrees   1/4
4:00     120 degrees  1/3 
5:00     150 degrees  5/12  
6:00     180 degrees  1/2  
7:00     210 degrees  7/12 
8:00     240 degrees  2/3 
9:00     270 degrees  3/4 
10:00   300 degrees  5/6  
11:00   330 degrees  11/12
12:00   360 degrees  12/12  noon or midnight

Thursday, December 8, 2011

12-8 Math Skills - Numerical pitch of Billie Jean notes



The bass riff to Billie Jean graphed as frequencies in Hz on the y-axis, and an internal field trip two floors down to investigate the pitches of piano notes.

Wednesday, December 7, 2011

12-2 notes - Point-slope form

Point-slope form is

y - ysub1 = m ( x - xsub1)  where x and y are variables, and xsub1 and ysub1 are values from a given ordered pair, from a given point.

After substituting, distribute on the right and move -ysub1 from the left side to the right side.  This isolates y on the left and leaves a slope times x term and a y-intercept term on the right.

12-6 Class notes - Standard form of a linear equation

(  ,  ) indicates an ordered pair, contains an x and a y, suggests the shape of a point

(  ,  ), (  ,  ) indicates two ordered pairs, has the four values needed to find a slope, suggests a line

m indicates a rate, a slope, a measure of slant, a rise over a run; m stands next to the x

indicates the height above the origin, it's the y-intercept, it gives the point (0, b)


The slope-intercept form  y = mx + b has the variable y by itself on one side of the = sign.

The standard form Ax + By = C has the constant C (a number) by itself on one side of the = sign.



A is the coefficient of x (a number that multiplies x)
B is the coefficeint of y (a number that multiplies y)

To change from slope-intercept form to standard form, isolate b, the y-intercept.  Move the mx term to the other side of the equal sign.



To change from standard form to slope-intercept form, move the Ax term away from the By term.  Divide both sides by B.  m, the slope, will be -A/B and b, the y-intercept, will be C/B.

11-30 notes - Slope-intercept form and tables



11-29 notes - Message plans



11-28 notes - Pressure at depth