Circle a and b are concircle roundgruent. ab equals 18 and cd equals 12. what is the radius of the circle. round to the nearest 10th place.

Step-by-step explanation:

A small secret: AC is the radius. It is also the hypotenuse of a right triangle. The two lines you have drawn in are perpendicular.

So 1/2 CD is one leg of the right triangle

And 1/2 AB is the other leg of the right triangle

1/2 CD= 1/2 *12 = 6

1/2 AB = 1/2 * 18 = 9

Let 1/2 CD = a

Let 1/2 AB = b

Let the radius = c

c^2 = 6^2 + 9^2

c^2 = 36 + 81

c^2 = 117                      Take the square root of both sides.

sqrt(c^2) = sqrt(117)

c = sqrt(3 * 3 * 13)  

The rule is to take out 1 of a pair of equal roots and throw the other away.

c = 3 * sqrt(13)

Since the radius = c, the answer is 10.82

To the nearest tenth, the answer is 10.8

the opening of this porabola is facing up

step-by-step explanation: