need some help with trig function: 4 sin(a + pi/6) cos(a - pi/6)

• 03-08-2018, 03:08 PM
chaNio
need some help with trig function: 4 sin(a + pi/6) cos(a - pi/6)
So i basically hate to solve this thing:

. . . . .$$4\, \sin\left(\alpha\, +\, \dfrac{\pi}{6}\right)\, \cos\left(\alpha\, -\, \dfrac{\pi}{6}\right)$$
• 03-08-2018, 03:40 PM
tkhunny
You would do well to find the Double Angle formula for sine. Hint: $$\sin(2x) = ...$$
• 03-08-2018, 03:55 PM
Dr.Peterson
tkhunny's suggestion is particularly apt if the expression is

4 sin(alpha + pi/6) cos(alpha + pi/6)

But it looks to me more like

4 sin(alpha + pi/6) cos(alpha - pi/6)

Am I right about that? (I'm also not sure I'm reading the "alpha" correctly.)

If so, then there are some identities called "product-to-sum" identities you can use; if you haven't seen them, they can be derived from the angle-sum and angle-difference identities.

Does any of that sound familiar?
• 03-09-2018, 03:26 PM
stapel
Quote:

Originally Posted by chaNio
So i basically hate to solve this thing:

. . . . .$$4\, \sin\left(\alpha\, +\, \dfrac{\pi}{6}\right)\, \cos\left(\alpha\, -\, \dfrac{\pi}{6}\right)$$

There is no "equals", so this is not an "equation" and cannot be "solved". What were the actual instructions?

When you reply, please include a clear listing of your thoughts and efforts so far. Thank you! ;)