How my query should looks like ?

Questions
1

Hello,
I have a challenge I’m not sure how to express it. here is the original question: “From the formula for sin (2t + t) find sin 3t in terms of sin t.”
The answer is -4 sin^3 (t) + 3sin (t)

Any help with on how the query should looks like.

Thank you ahead
Tal

2

Hi Tal, the function you are looking for is probably TrigExpand,

TrigExpand[Sin[3t]]