Answer:
DA = 285.7 m
Step-by-step explanation:
First we need to find the side AB in the triangle ABC, and we can do this using Pythagoras' theorem:
AB^2 = BC^2 + AC^2
AB^2 = 300^2 + 400^2
AB^2 = 25000
AB = 500 m
We can find the angle ABC with the tangent relation:
tangent(ABC) = 400/300 = 4/3
ABC = 53.13°
From triangle ABC, we have:
ABC + BCA + CAB = 180°
53.13 + 90 + CAB = 180
CAB = 36.87°
From triangle DAC, we have:
DAC + ACD + CDA = 180
36.87 + 45 + CDA = 180
CDA = 98.13°
Now to find the side of DA, we can use law of sines in triangle DAC:
DA/sin(DCA) = AC/sin(CDA)
DA/sin(45) = 400/sin(98.13)
DA = 400 * 0.7071 / 0.9899 = 285.7258 m
Rounding to nearest tenth, we have DA = 285.7 m
