DOES ANYONE KNOW THE ANSWER NEED HELP PLEASE ASAP!

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  (A)  -1

Step-by-step explanation:

I find it easiest to determine the angles x and y, then find the sine of their difference.

  x = arccos(1/2) = 60°

  y = arcsin(1/2) = 180° -30° = 150° . . . . . . for 2nd-quadrant angle

Then ...

  sin(x -y) = sin(60° -150°) = sin(-90°)

  sin(x -y) = -1

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Alternatively, you can find the other trig functions of the angles and use the formula for the sine of a difference.

  sin(x) = √(1 -(1/2)²) = (√3)/2

  cos(y) = -√(1 -(1/2)²) = -(√3)/2 . . . . 2nd quadrant angle

Then ...

  sin(x -y) = sin(x)cos(y) -cos(x)sin(y)

  sin(x -y) = (√3)/2·(-√3)/2 -(1/2)·(1/2) = -3/4 -1/4

  sin(x -y) = -1

he spend 5.1 minutes chatting with his friends.

step-by-step explanation:

2/5+1/2=9/10

6/1-9/10=5.1