Answer:
answers are: (-1,-2), (1,2), (-1,5), (1,-5). in other words, option 2, 6, 7, and 8.
Step-by-step explanation:
hope it helps
The double angle formula for the sine is

The right hand side is exactly your expression, where 
So, rewriting the expression from right to left, we have

Answer:
t55=d
Step-by-step explanation:
55 is mph and since t is time t would be multiplied by 55
I think x = 78
because 21/14 = 1.5
so x = 1.5*52
x = 78