Answer:
3.6
Step-by-step explanation:
It can be seen from the diagram that ΔDAC and ΔABD are right angled triangle.
Using the SOH, CAH, TOA trigonometry identity on ΔDAC where;
AC is the hypotenuse = 5.1
CD is the opposite (since it faces the angle directly)
According to SOH;
Sin[tex]\theta[/tex] = opp/hyp
sin[tex]\theta = \frac{3.2}{5.1}[/tex]
[tex]sin\theta = 0.6275\\\theta = sin^{-1} 0.6275\\\theta = 38.9^{0}[/tex]
∠DAC = ∠BAD = 38.9°
According to ΔABD, the opposite side is DB which is unknown and the hypotenuse id AB i.e 5.7
Using SOH;
[tex]sin BAD = opp/hyp\\sin \theta = BD/AB\\sin 38.9^{0} = BD/5.7\\BD = 5.7 sin 38.9^{0}\\BD = 3.58\\[/tex]
BD ≈ 3.6 to one dp