Question

(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) =

Answer 1

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

Answer 2

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

Answer 3

helps ?

Answer 4

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

Answer 5

a = -8 cos (5pi/6)

Answer 6

okaay so i have to answer in radiants

Answer 7

http://upload.wikimedia.org/wikipedia/commons/thumb/4/4c/Unit_circle_angles_color.svg/300px-Unit_circle_angles_color.svg.png

Answer 8

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

Answer 9

x(5pi/6)=-4sqroot3

Answer 10

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

Answer 11

okaay

Answer 12

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

Answer 13

v(t)=-4

Answer 14

a(t)=4sqroot3

Answer 15

v(5π/6)=-4 .. right

Answer 16

a(5pi/6) right as well

Answer 17

thank you guys learned alot

Answer 18

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 \(\frac{\sqrt{4}}{2}\)

Answer 19

thank you