## lilsis76 2 years ago just a question. how can i find cos5pi/2 ? where is that on the unit circle?

1. Kyleia

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2. lilsis76

so i kep going around?

3. ByteMe

5pi/2 is coterminal with pi/2

4. lilsis76

what is coterminal?

5. ByteMe

an angle has a initial side (positive x-axis), and a terminal side... it means that their terminal sides are the same.

6. ByteMe

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7. lilsis76

oh...okay, so then pi/3 would be 15pi/3?

8. ByteMe

no... they have to differ by MULTIPLES of 2pi... notice that 5pi/2 = 2pi + pi/2 but 15pi/3 = 5pi, not a multiple of 2pi.

9. lilsis76

hmmmm...................... :( im getting badder at this. ugh. okay ill post a new question cuz this one i superly need help on

10. ByteMe

think of it this way.... they differ by 2pi because 2pi is just a full rotation... so think of 30 degrees... 30 degrees is coterminal with 390 degrees because all you're doing is adding a full rotation 360 degrees: 30 + 360 = 390

11. lilsis76

okay, i think i see it