Answer:
![|AB|=30](https://img.qammunity.org/2020/formulas/mathematics/college/cgjqszg81xjhr922n9rjk9gmei8aqcupwi.png)
Explanation:
From the diagram,
AO=OC=16 units, all radii of a circle are equal.
BO=OC+BC
BO=16+18
BO=34
A tangent to a circle will always meet the radius at right angles.
We use the Pythagoras Theorem to obtain:
![|AB|^2+|AO|^2=|BO|^2](https://img.qammunity.org/2020/formulas/mathematics/college/t4hd2dzru4na3v04jso01f3pxgowjt77pd.png)
![|AB|^2+16^2=34^2](https://img.qammunity.org/2020/formulas/mathematics/college/nvzqq5rtgt2yazlzaotdp8tlu6tvelifql.png)
![|AB|^2+256=1156](https://img.qammunity.org/2020/formulas/mathematics/college/1sda6iy71lgl1dag8wmj2q233qdmjhgwjb.png)
![|AB|^2=1156-256](https://img.qammunity.org/2020/formulas/mathematics/college/xn72jj8r39qprx5k8fayviu2ckybrki0mm.png)
![|AB|^2=900](https://img.qammunity.org/2020/formulas/mathematics/college/f5gv26xun81p58sjj0n5u28cu2wmmriruh.png)
Take positive square roots to get:
![|AB|=√(900)](https://img.qammunity.org/2020/formulas/mathematics/college/o2x7dvihosgtsq9jkevq9j5bdg76qmtu1n.png)
![|AB|=30](https://img.qammunity.org/2020/formulas/mathematics/college/cgjqszg81xjhr922n9rjk9gmei8aqcupwi.png)