We can use the Pythagorean Trigonometric Identity which says:

Since we need to find sin(t), we have to solve for it:

Let's plug in the given cos(t) value:

And solve sin(t):

Simplify further:

And it all simplifies down to:

Since it's in the 4th quadrant, the sin(t) value is going to be negative. So, your final answer is:

Hope this helps!
c. No. You have a probability of winning, while your friend has a
probability of winning.
Or it’s A
Let's analyse the function

The amplitude is A, so we want A=1.5
Now, we start at x=0, and we have 
After one second, i.e. x=1, we want this sine function to make 330 cycles, i.e. the argument must be 
So, we have

so, the function is
