## anonymous 3 years ago (b) Find the position, velocity, and acceleration of the mass at time t = 5π/6. x(t) = 8 cos t v(t) = -8sint a(t) = -8cost x(5π/6)= v(5π/6)= a(5π/6) =

1. anonymous

i get decimals for the answers, i'm just wonder how i would answer it on a test

2. anonymous

cos(5pi/6) = -sqrt(3)/2 sin(5pi/6) = 0.5

3. anonymous

helps ?

4. phi

you should memorize sin,cos and tan of 0,30,45, 60 and 90 degrees you should know how to change between radians and degrees radians *180/pi or degrees*pi/180 you should know how to figure out the signs depending on which quadrant you are in for sin, cos, tan

5. cwrw238

a = -8 cos (5pi/6)

6. anonymous

7. anonymous
8. phi

if I were doing this, I would say 5pi/6 is the same as 30 degrees in the 2nd quadrant. sin will be +, cos -

9. anonymous

x(5pi/6)=-4sqroot3

10. anonymous

That is correct for 8cos(5pi / 6)

11. anonymous

okaay

12. anonymous

So you have the concept, just apply it to the rest.

13. anonymous

v(t)=-4

14. anonymous

a(t)=4sqroot3

15. anonymous

v(5π/6)=-4 .. right

16. anonymous

a(5pi/6) right as well

17. anonymous

thank you guys learned alot

18. phi

I don't know that it really helps me memorize sin of these angles, it is interesting: angle sin(angle) 0 $$\frac{\sqrt{0}}{2}$$ 30 $$\frac{\sqrt{1}}{2}$$ 45 $$\frac{\sqrt{2}}{2}$$ 60 $$\frac{\sqrt{3}}{2}$$ 90 $$\frac{\sqrt{4}}{2}$$

19. anonymous

thank you