Help with composite trig functions please

Kuroki

New member
Joined
Sep 29, 2012
Messages
4
Hi I need help understanding/solving composite trig functions
The example I have involves sin: arcsin(sin(3pi/5))
I know the property of arsin(sin(theata)) = theta IF theta is between [-pi/2, pi/2]
However this is not the case...so I need to somehow make it apply is what I've been told.
I know I can rewrite it as sin(theta) = sin (3pi/5)
And I really don't know how you get 2pi/5 as the answer from that.
Any help would be appreciated :)

~K
 
Hi I need help understanding/solving composite trig functions
The example I have involves sin: arcsin(sin(3pi/5))
I know the property of arsin(sin(theata)) = theta IF theta is between [-pi/2, pi/2]
However this is not the case...so I need to somehow make it apply is what I've been told.
I know I can rewrite it as sin(theta) = sin (3pi/5)

You know sin(π - Θ) = sin(Θ)

so

sin(3π/5) = sin(π - 3π/5) = sin(2π/5)


And I really don't know how you get 2pi/5 as the answer from that.
Any help would be appreciated :)

~K
.
 
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