The Pythagorean theorem tells you the relationship between the various lengths is ...
cd² = ac² +ad²
cd² = (2.4 m)² + (1.8 m)² = 9.00 m²
cd = √(9.00 m²) = 3.0 m
Since cd = cb and ab = ac+cb, we have ...
ab = 2.4 m + 3.0 m = 5.4 m
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You may recognize this as a 3-4-5 right triangle with a scale factor of 0.6. We are asked for the sum of the lengths of the "4" and "5" legs, which is ...
