You have show that the condition for stationary points is that tanx = 1
In the next part we actually have to find those points,
that is, solve
tanx = 1
x = 45° or x = 225°
or
x = π/4 or x = 5π/4 radians
when x = π/4
y = e^-π/4 sin π/4 = .3224
when x = 5π/4
y = e^-5π/4 sin 5π/4 = -.011139
Looking at your domain, I think you made a typo, and I will assume you meant
-π < x < π
so the second point above lies outside the domain,
but there is another solution of
x = -135° or -3π/4
if x = -3π/4
y = e^-3π/4 sin 3π/4 = -.067
Within your domain, the stationary points are
(π/4, .3224) and (-3π/4, -.067)
9. consider the function y=e^-x sin x where pie < x < pie
find dy/dx which is e^-x(cos x - sin x)
show that at stationary points, tan x = 1. - I have done this part
I don't understand this part:
How do I do this: determine the co-ordinates of the stationary points correct to 2 dp.
Could you tell me how to start off this question?
1 answer