Help with ratios of double angle problem!! (1 Viewer)

[ScienceGuy99]

Hi there! Prelim extension 1

I can't understand (or get the answer for) question 7a in exercise 6.15 in the maths in focus textbook.

For those without that textbook, the question is:

"By writing 3x as 2x + x, find an expression in terms of x for:
a) Sin3x"

The answer is (3sinx)(cos^2x) - sin^3x

I'm substituting theta for x because I can't type theta haha

 

[Drongoski]