Trigonometry unit circle question (see photo)

The answer is Choice A: (cos(theta), sin(theta))

More specifically x = cos(theta) and y = sin(theta) make up the point (x,y) which is where point P is located. Because we have a unit circle, the equation of the circle is x^2+y^2 = 1. This leads to cos^2(theta) + sin^2(theta) = 1 which is the pythagorean trig identity. 

10 units

Step-by-step explanation:

Point A (3,-1)

Point B (-5,5)

Distance between them,

√{(-5-3)²+(5-(-1))²}

= √{(-8)²+6²}

= √(64+36)

= √100

= 10 units