Answer:
20 units
Explanation:
to solve this equation you need the pythagorean theorem: a^2 + b^2 = c^2
2^2 + 7^2 = 53; square root of 53 is 7.28010989; or about 7.3 units (line AC)
2^2 + 6^2 = 40; square root of 40 is 6.32455532; or about 6.3 units (line BC)
4^2 + 5^2 = 41; square root of 41 is 6.40312424; or about 6.4 units (line AB)
7.3 + 6.3 + 6.4 = 20
20 units