10. 24x-8. 11. 5x+6x+2x+15x=28x I hope this is right
A few ways. you can enter it into a calculator for one, but the easiest way would be to reference a unit circle and look for an ordered pair where sin (the y value), is equal to -1/2
on a unit circle, the sin value is -1/2 at 7pi/6 and 11pi/6
because sin is the y value, it will additionally be in the quadrants III or IV based on the fact that (-1/2) as a sin value IS a negative and would have to be found in a quadrant in which sin is negative (the lower half of a coordinate plane, in this case)
Answer:

Step-by-step explanation:
Using the law if indices
×
= 
Thus to simplify the expression add the 3 exponents
a(b + c) + b(c - a) + c(a - b) ← distribute parenthesis
= ab + ac + bc - ab + ac - bc ← collect like terms
= 2ac
Then the expression simplifies to

Hope this helps, your welcome :)