What is the amplitude of the sinusoid given by y=-3sin(5x)?

Please explain answer. Thank you!

Question

What is the amplitude of the sinusoid given by y=-3sin(5x)?

Please explain answer. Thank you!

jhannybean · Answer

$$F(t) = Af(Bt – C) + D$$ The formula for basic trig functions where $\sf f(x)$ is your function. 

A = amplitude in this case.

So comparing your function: $F(x) = -3\sin(5x)$ 
What do you think the Amplitude might be?

kj4uts · Answer

Would that make it 3 then? @Jhannybean

jhannybean · Answer

Yes :) don't forget the negative sign that accompanies it!

kj4uts · Answer

So how would I right the answer then?

kj4uts · Answer

like this -3?

jhannybean · Answer

You were partially right, but the negative is part of the 3 so you can't just leave it out

jhannybean · Answer

Yes :) like that.

kj4uts · Answer

so -3 but isn't that how its listed in the original problem y=-3sin(5x) and the answer is -3?

jhannybean · Answer

Oh, I am sorry. I understood it wrong as well.

jhannybean · Answer

$$\text{Amp} = |A| = |-3| = 3$$