Heaviside/step function question

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Homework Statement


Hey so this is a really trivial question.

f(t) = { 0, 0<= t < pi
{ -sin3t, t>=pi

Just having trouble properly shifting this!

The Attempt at a Solution



f(t) = -upi(t)sin(3t)

= -upi(t)sin[3(t-pi+pi)]

= upi(t)sin[3(t-pi+pi)]

How do I take the +pi out?
I know it should end up as:

upi(t)sin[3(t-pi)]

I just don't really understand how from my last step.
thanks for reading!
 

Answers and Replies

  • #2
vela
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Homework Statement


Hey so this is a really trivial question.

f(t) = { 0, 0<= t < pi
{ -sin3t, t>=pi

Just having trouble properly shifting this!

The Attempt at a Solution



f(t) = -upi(t)sin(3t)

= -upi(t)sin[3(t-pi+pi)]

= upi(t)sin[3(t-pi+pi)]
What happened to the minus sign?
How do I take the +pi out?
I know it should end up as:

upi(t)sin[3(t-pi)]

I just don't really understand how from my last step.
thanks for reading!
Hint: 3(t-pi+pi)=3(t-pi)+3pi
 

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