Answer:
r=1
Step-by-step explanation:
First we need to know the length of each side of the triangle, so we use the formula of the vector modulus:

By doing so, we find:

With this we know that the triangle is not right, but, we assume the longest side as the hypotenuse of the problem.
As we have two equal sides, we know that the line between point |AB| and the center of the hypotenuse is perpendicular, therefore, we can calculate it using Pythagoras theorem:

Answer: choice D) 5/2
The csc or cosecant value is the reciprocal of the sine value. All you do is flip the fraction given. In terms of notation, we can say csc(theta) = 1/sin(theta). If sin(theta) = a/b, then csc(theta) = b/a.
The answer is choice D
Check out the attached image to see the steps on how to get that answer
Notice how I'm marking the rows and columns, and then multiplying the corresponding values together. Also make note of the color-coding.