Point P moves around the circle unit. The angle x, in radius,changes with time as shown. (a) Estimate the corrdinates of P when t = 2. (b) When t = 2, approximately how fast is the point P moving in the x-direction? In the y-direction?
when t = 2, x about = 3.2; when t =4, x about = 5.5; when t = 6, x about = 6.1; when t = 8, x about = 6.2; when t = 10, x about = 6.2
The answer is (a) (-0.99, -0.16) (b) vx = 0.32, vy = -1.98
I don't know how to get the answer, please help.
Maths Cal (rates and related rates)
2007-05-11 2:38 pm
回答 (1)
2007-05-11 4:26 pm
✔ 最佳答案
t=2,x=3.2we have x=1.6t
since the coordinates of P can be represented as (cosx, sinx)=(cos1.6t, sin1.6t)
dP/dt=(-1.6sin1.6t,1.6cos1.6t)
(a)
the corrdinates of P when t = 2 is
(cos 3.2, sin3.2)
=(-0.99, -0.16)
(b)
When t = 2, the point P moving in the x-direction is
-1.6sin1.6t
=0.32
When t = 2, the point P moving in the y-direction is
1.6cos1.6t
=-1.98
收錄日期: 2021-04-25 16:54:33
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