If you mark the points on the graph, all three sides have different lengths and angles, therefor it is a scalene triangle.
It cannot be a right triangke bc there is no right angle, and no obtuse either so that crosses out obtuse as an option as well. In order to be an isoceles triangle it must have two sides of equal length, but it does not.
in a circle, and central 
, you can see that the part "sliced out" by the central angle is 
of the whole circle.
is 
of the circumference of the circle. So,