Answer:
b. 6.93 m.
Step-by-step explanation:
We have been given triangle ABC and we are asked to find the measure of a.
We will use law of sines to solve our given problem.
, where a, b and c are opposite sides of angle A, B and C respectively.
First of all, we will find the measure of angle B using angle sum property.
![\angle A+\angle B+\angle C=180^{\circ}](https://tex.z-dn.net/?f=%5Cangle%20A%2B%5Cangle%20B%2B%5Cangle%20C%3D180%5E%7B%5Ccirc%7D)
![30^{\circ}+\angle B+90^{\circ}=180^{\circ}](https://tex.z-dn.net/?f=30%5E%7B%5Ccirc%7D%2B%5Cangle%20B%2B90%5E%7B%5Ccirc%7D%3D180%5E%7B%5Ccirc%7D)
![\angle B+120^{\circ}=180^{\circ}](https://tex.z-dn.net/?f=%5Cangle%20B%2B120%5E%7B%5Ccirc%7D%3D180%5E%7B%5Ccirc%7D)
![\angle B=180^{\circ}-120^{\circ}](https://tex.z-dn.net/?f=%5Cangle%20B%3D180%5E%7B%5Ccirc%7D-120%5E%7B%5Ccirc%7D)
![\angle B=60^{\circ}](https://tex.z-dn.net/?f=%5Cangle%20B%3D60%5E%7B%5Ccirc%7D)
Upon substituting our given values in law of sines we will get,
![\frac{a}{\text{Sin}(30^{\circ})}=\frac{12}{\text{Sin}(60^{\circ})}](https://tex.z-dn.net/?f=%5Cfrac%7Ba%7D%7B%5Ctext%7BSin%7D%2830%5E%7B%5Ccirc%7D%29%7D%3D%5Cfrac%7B12%7D%7B%5Ctext%7BSin%7D%2860%5E%7B%5Ccirc%7D%29%7D)
![\frac{a}{0.5}=\frac{12}{\frac{\sqrt{3}}{2}}](https://tex.z-dn.net/?f=%5Cfrac%7Ba%7D%7B0.5%7D%3D%5Cfrac%7B12%7D%7B%5Cfrac%7B%5Csqrt%7B3%7D%7D%7B2%7D%7D)
![\frac{a}{0.5}=\frac{2*12}{\sqrt{3}}](https://tex.z-dn.net/?f=%5Cfrac%7Ba%7D%7B0.5%7D%3D%5Cfrac%7B2%2A12%7D%7B%5Csqrt%7B3%7D%7D)
![\frac{a}{0.5}*0.5=\frac{24}{\sqrt{3}}*0.5](https://tex.z-dn.net/?f=%5Cfrac%7Ba%7D%7B0.5%7D%2A0.5%3D%5Cfrac%7B24%7D%7B%5Csqrt%7B3%7D%7D%2A0.5)
![a=\frac{12}{\sqrt{3}}](https://tex.z-dn.net/?f=a%3D%5Cfrac%7B12%7D%7B%5Csqrt%7B3%7D%7D)
![a=6.9282032302755\approx 6.93](https://tex.z-dn.net/?f=a%3D6.9282032302755%5Capprox%206.93)
Therefore, the value of a is 6.93 meters and option 'b' is the correct choice.