The diameter and hught of this cylinder are equal to the side length, s, of the cube in wich cylinder is inscribed. what is the expression for the cylinder's volumes ?

The fomula for the volume of a cylinder is

... V = πr²·h

You have r=s/2 and h=s, so this becomes

... V = π(s/2)²·s

... V = (π/4)s³

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.

not sure but it may be b, as i said i'm not sure.