I dont understand how the scale on my graph works.?

Question

Hi, I asked a question related to what I am going to ask now about an hour ago. With Cos /Sin graphs, it is said that if you divide the period by 4, that is the increment you use to then calculate the other numbers that make up the scale on the graph. I tried to do this but it isnt making any sense to me.

Lets start with my equation: y=0.5cos 8x. 8x=B

Period=2pie/B. 2pie/8= Pie/4. Ok, so this value is now at the end of my graph and is the period. To get the subsequent value next to it, I'm supposed to divide Pie/4 by 4. This = pie/8 no? So, to get the next value, I add pie/8 onto pie/4. How do I add these and what does it equal? God, I must of missed out on fractions somewhere in Primary school, I did move schools alot. This looks simple I just can't figure it out.

Answer 1

y=0.5cos 8x

y = a cos bx

b = 8 so the period = 2pie/8 = pie/4

dividing by 4

pi...........4

---divide ---- =

4............1

pi.............1

---Multiply ---- =

4..............4

pie/16

Adding pie/4 add pie/16

(pie/4) + (pie/16)  LCD = 16

mulitply pie/4 by 4

(pie/4)(4/4) + (pie/16)

(4pi/16) + (pie/16) = 5pie/16