Answer:
AB = 14.0 cm
Step-by-step explanation:
This requires us to use the Pythagorean Theorem twice.
We have (20 cm)^2 = (6 cm)^2 + (AC)^2
(AB)^2 + (BC)^2 = (AC)^2
BC = 13 cm
(AB)^2 = (AC)^2 - (BC)^2
(20 cm)^2 = (6 cm)^2 + (AC)^2
(AC)^2 = (20 cm)^2 - (6 cm)^2
so...
(AB)^2 = 20^2 - 6^2 - 13^2
(AB)^2 = 400 - 36 - 169 = 195
AB = root(195) = 13.964 cm
rounded AB = 14.0 cm
