What determines the size of a circle

The circumference of a circle is directly proportional to its radius. The ratio between a circle's circumference and its diameter is pi, a constant that equals approximately 3.142. The circle's diameter, in turn equals twice the radius. A regular solid that has a circle as a face is called a cylinder.

Step-by-step explanation:

2. angles qrt and qst both measures 156 degrees.

step-by-step explanation:  

we have been given a diagram of a circle and we are told that measure of arc qvt is 156 degrees.  

we can see from our given diagram that angle qrt and angle qst subtends to arc qvt.

since we know that angles subtended by the same arc at the circumference are always equal.

by angle subtended by same arc theorem, measure of angle qrt and angle qst will be equal to the measure of arc qvt.

therefore, angles qrt and qst both measures 156 degrees and 2nd statement is the correct choice.