Which is true regarding chords and diameters of circles?
both chords and diameters have two endpoints on a circle. diameters must intersect the center of a circle.
both chords and diameters have two endpoints on a circle. chords must intersect the center of a circle.
chords have two endpoints on a circle. diameters have one endpoint on a circle and one at the center.
chords have one endpoint on a circle and one at the center. diameters have two endpoints on a circle.

the correct answers are the following:

1. both chords and diameters have two endpoints on a circle.

this is true. chords are straight lines whose endpoints lie on a circle. this is indicated as the red line in figure 1. notice that the endpoints lie on the circle. on the other hand, diameters also have two endpoints on a circle as indicates the blue line in figure 2.

2. diameters must intersect the center of a circle.

this is true. one important feature of diameters is that they must intersect the center of the circle. this is shown in figure 2. so, diameters are:

3. parallelogram

step-by-step explanation:

we turn each of our sides into direction vectors

ab=b-a=(3 - 7, 1 - 0) = (-4, 1)

bc=c-b=(1,6)

cd=d-c=(4,-1)

da=a-d=(-1,-6)

we see how the opposite sides have negated direction vectors; this is characteristic of a parallelogram.   we have congruent sides ab=cd and bc=da with unequal lengths because 1^2+6^2 is different from (-4)^2+1^2.   so it's not a square or a rhombus.  

we check the dot product of direction vectors of adjacent sides.   we have

ab dot bc = -4(1) + 1(6) = 2

that's not zero so the sides are not perpendicular.   we've ruled out rectangle.

the direction vectors indicate two pairs of congruent parallel sides, so we choose parallelogram over trapezoid.

the f

last graph i believe

step-by-step explanation:

worked it out i believe