Answer:
we should know that :
sin ( a + b ) = sin a * cos b + sin b cos a
For the given equation :
sin (π + q) = sin π * cos q + sin q * cos π
sin π = zero and cos π = -1
∴ sin (π + q) = 0 * cos q + sin q * (-1) = - sin q
<u>Another solution:</u>
The angle (π + q) lies in the third quarter ⇒ (1)
(π + q) and (-q) are supplementary angles ⇒ (2)
From (1) and (2)
sin(π + q) = -sin q
Answer:

Step-by-step explanation:
To answer this problem, we must bear in mind that the express train travels 3 times faster than the freight train.
If we call F the distance that the freight train travels and we call E at the distance that the express train travels, we must have the distance between them after 15 minutes it must be 30 miles.
So

We also know that:
Since the express train travels 3 times faster than the freight train.
So, like both equations, we have to:

Then
miles in the opposite direction.
This is the distance you traveled in 15 minutes.
Therefore, the speed of the express train (
) is the distance traveled between the time it did

Answer:
16
Step-by-step explanation:
group the first 2 terms into (8*8) and the second two into (8*6). this gets you 8*8-8*6 which can be grouped into 8*2 which is 16