Answer:
![a\approx7.2](https://tex.z-dn.net/?f=a%5Capprox7.2)
Step-by-step explanation:
The given problem presents one with the following information:
- Triangle ABC
- Side (b) has a measure of (13.5)
- Side (c) has a measure of (8.9)
- Angle (A) has a measure of (29)
To solve this problem, one can use the law of cosines. The law of cosines is a property that can apply to any triangle. This property comes in the form of a formula, which is as follows:
![a^2=\sqrt{b^2+c^2-2bc(cos(A))}](https://tex.z-dn.net/?f=a%5E2%3D%5Csqrt%7Bb%5E2%2Bc%5E2-2bc%28cos%28A%29%29%7D)
Where (a), (b), and (c) are sides of the triangle, and (<A) is the angle opposite the side (a).
Substitute the given information into the formula and solve for the unknown side (a):
![a=\sqrt{b^2+c^2-2bc(cos(A))}](https://tex.z-dn.net/?f=a%3D%5Csqrt%7Bb%5E2%2Bc%5E2-2bc%28cos%28A%29%29%7D)
![a=\sqrt{(13.5)^2+(8.9)^2-2(13.5)(8.9)(cos(29))}](https://tex.z-dn.net/?f=a%3D%5Csqrt%7B%2813.5%29%5E2%2B%288.9%29%5E2-2%2813.5%29%288.9%29%28cos%2829%29%29%7D)
Simplify,
![a=\sqrt{(13.5)^2+(8.9)^2-2(13.5)(8.9)(cos(29))}](https://tex.z-dn.net/?f=a%3D%5Csqrt%7B%2813.5%29%5E2%2B%288.9%29%5E2-2%2813.5%29%288.9%29%28cos%2829%29%29%7D)
![a=\sqrt{182.25+79.21-240.3(cos(29))}](https://tex.z-dn.net/?f=a%3D%5Csqrt%7B182.25%2B79.21-240.3%28cos%2829%29%29%7D)
![a=\sqrt{261.46-240.3(cos(29))}](https://tex.z-dn.net/?f=a%3D%5Csqrt%7B261.46-240.3%28cos%2829%29%29%7D)
![a=\sqrt{261.46-210.1711}](https://tex.z-dn.net/?f=a%3D%5Csqrt%7B261.46-210.1711%7D)
![a=\sqrt{51.2889}](https://tex.z-dn.net/?f=a%3D%5Csqrt%7B51.2889%7D)
![a\approx7.2](https://tex.z-dn.net/?f=a%5Capprox7.2)