SOLUTION
Given the question in the image, the following are the solution steps to answer the question.
STEP 1: Write the trigonometric ratios
[tex]\begin{gathered} \sin\theta=\frac{opposite}{hypotensue} \\ \cos\theta=\frac{adjacent}{hypotenuse} \\ \tan\theta=\frac{opposite}{adjacent} \end{gathered}[/tex]
STEP 2: Analyze the given scenario to get the details given
We were given the length of the piece of wood needed to make the ramp as 3.5m long, this implies that the length of the side is 3.5m. From the given image, this is the hypotenuse.
[tex]hypotenuse=3.5m[/tex]
The angle of elevation is 28 degrees,
[tex]\theta=28\degree[/tex]
The height of the platform from the image will be opposite since it is the side that is facing the angle 28 degrees.
[tex]opposite=height\text{ }of\text{ }platform[/tex]
Joining all these together, we have a right-angled triangle given below:
From the given ratios in step 1, since we know tha hypotenuse and the opposite and also the theta, therefore the correct ratio to use is:
[tex]\begin{gathered} \sin\theta=\frac{opposite}{hypotenuse} \\ \\ \sin28=\frac{height}{3.5} \\ height=3.5\times\sin28 \end{gathered}[/tex]
Therefore, the given claim of needing tangent ratio to find the height of the platform is not a reasonable approach because the adjacent which is the base is not given.
