There are 24 permutations.
The number of permutations of 4 objects taken 4 at a time is given by
4!/(4-4)! = 4!/0! = 4!/1 = 4! = 24
E^2=0.36 take the square root of both sides
e=±0.6
Answer: sqrt(2)/2 which is choice D
======================================================
Explanation
(3pi/4) radians converts to 135 degrees after multiplying by the conversion factor (180/pi).
The angle 135 degrees is in quadrant 2. We subtract the angle 135 from 180 to find the reference angle
180-135 = 45
Then you can use a 45-45-90 triangle to determine that the ratio of opposite over hypotenuse is sqrt(2)/2
sine is positive in quadrant 2
------------
Alternatively, you can use a unit circle. Refer to the diagram below. In red, I've circled the angle 3pi/4 radians. The terminal point for this angle has a y coordinate of sqrt(2)/2
Recall that y = sin(theta).
Answer: 4
Step-by-step explanation: