If point

is on the unit ircle, then:

Since, the point is in the second quadrant, x is negative.
Thus,

Part A:

Therefore,

.
Part B:

Therefore,
Just put these values in the place of x and solve!
The answer is 2 btw
Yes ABD=CBD since they both are just half of the triangle
KE = 1/2(m * v^2)
KE = 1/2(1350 * 12^2)
KE = 1/2(1350 * 144)
KE = 1/2(194,400)
KE = 97,200 Joules