ok last week went quite smoothly. we started chapter 7. i have to say that trigonometry isn't as bad as i thought it was gonna be and plus we only did what like two sections. here is an explanation for what is covered in 7.1 :
Angles:
- measured in degrees (°), minutes ('), and seconds (")
- to find minutes multiply what is behind the decimal by 60
- to find seconds multiply what is behind decimal of minutes by 60; divide by 3600 to get decimal
- angles are measuredd in degrees & radians: radians= ° x π/180, degrees= radians x 180/π (always use the exact answer and don't plug π in calc.)
- to find coterminal angles add or substract 360° or 2π
- HINTS- must use ° symbol if in degrees or your answer is WRONG. (if there is no ° symbol then it is assumed that your answer is in radians)
Examples:
1. write as minutes & and seconds ( ' & " ) :
12.3°
12°(.36 x 60)'
12° 18'
2. find the decimal:
25° 20' 6"
25 + 20/60 + 6/3600
25.335°
3. degrees to radians:
36 x π/180 = 36/180 π = 1/5 π = π/5
4. find a negative coterminal angle
1125°
1125 - 3600 = - 315
alright now for what i don't understand is #13 on page 265. does anyone know how to did because i don't got clue...oh i might be wrong but people i think we have quiz on 7.1 & 7.2 on monday so be prepared..
Yay! Something I can actually comment on while making myself feel useful!
ReplyDelete#13 Goes:
A CD player uses a laser to read music from a disc. The player varies the rotational speed of the disc depending on the position of the laser. When the laser is at the outer edge of the disc, the player spins the disc at its slowest speed, 200 rpm.
A. At the slowest speed, through how many degrees does the disc turn in a minute? Through how many radians does it turn in a minute?
If one revolution is 2π or 360°, then 200 revolution/1 minute is 400π or 72,000°.
B. If the diameter of the disc is 11.9cm, find the approximate distance that a point on the outer edge travels in 1 min.
Multiply 11.9cm × 200rpm to find total distance: 2380cm/min
C. Use the preceding information to give the speed in cm/s
2380cm/min ÷ 60 seconds = 39&2/3
These questions are based more on the concepts of Section 1; all you're really doing is finding coterminal angles.
Hope this helps!