Bc is tangent to circle a at b and to circle d at c. what is ad to the nearest tenth?

a. 21.6
b. 19.3
c. 18.1
d. 18.7

(C) 18.1

Step-by-step explanation:

Given: BC is tangent to circle A at B and to circle D at C.

Construction:Join DE such that DE=BC=18.

Solution: Since the radius of the circle A is BA=7 and the radius of the circle D is CD=5, then EA=7-5=2.

Now, from the ΔDEA, we have

⇒

⇒

⇒

⇒

Therefore, the value of AD is 18.1.