Answer:
Correct option: First one -> 16 mm
Explanation:
The equilateral triangle has its three sides with the same length.
So if the perimeter is 96 mm, we have:
![Perimeter = 3*side](https://img.qammunity.org/2021/formulas/mathematics/high-school/h3l1d5k7b0dw70zhpo6l6ebfxlgpamnun5.png)
![3*side = 96](https://img.qammunity.org/2021/formulas/mathematics/high-school/kppxgcqnzvyh09d1okiwufqz28urlbtitr.png)
![side = 32 mm](https://img.qammunity.org/2021/formulas/mathematics/high-school/ksfvgeps4qmswow4bmiihccxzmskvyrm4l.png)
The segment MA is the height of the equilateral triangle, and its length can be calculated with the equation:
![height = (side * √(3))/(2)](https://img.qammunity.org/2021/formulas/mathematics/high-school/xq9dq5p15i8k8i3h8fnj0xz5ei82a2pzqw.png)
![height = 16√(3)](https://img.qammunity.org/2021/formulas/mathematics/high-school/tt82shgcrhffm81wspq3z88lw9py65rd4f.png)
Using the Pythagoras' theorem in the triangle ACM, we have:
![side^2 = MC^2 + height^2](https://img.qammunity.org/2021/formulas/mathematics/high-school/9j4h1pm5vp6z8nkhkxx1qrjzrmku56y7ze.png)
![1024 = MC^2 + 768](https://img.qammunity.org/2021/formulas/mathematics/high-school/9gxkg3ag7t9hovlxkt7gaiqkbo7afje5py.png)
![MC^2 = 256](https://img.qammunity.org/2021/formulas/mathematics/high-school/1dhqw3j8t8y8k8k1gowzak9qesmbizqru6.png)
![MC = 16\ mm](https://img.qammunity.org/2021/formulas/mathematics/high-school/gjb8eetk907oa69wqfimbrlrnq81fpkcsp.png)
Correct option: First one