Answer:
Last choice is correct.
Step-by-step explanation:
Given that ∠C=90°, ∠B=30°, c=10
We know that sum of all angles in a triangle is 180 degree.
∠A+∠B+∠C=180°
∠A+∠30°+∠90°=180°
∠A+∠120°=180°
∠A=60°
Now we can use sin or cos whichever applicable to find missing sides
[tex]\sin\left(30\right)=\frac{AC}{AB}[/tex]
[tex]\frac{1}{2}=\frac{b}{10}[/tex]
2b=10
b=5
Similarly
[tex]\cos\left(30\right)=\frac{BC}{AB}[/tex]
[tex]\frac{\sqrt{3}}{2}=\frac{a}{10}[/tex]
[tex]2a=10\sqrt{3}[/tex]
[tex]a=5\sqrt{3}[/tex]
a=8.6602
Hence last choice is correct.
