Answer:
all work is pictured and shown
The surface area of the right triangular prism is 270 sq ft
<h3>Total surface ara of the prism</h3>
The total surface area of the prism is the sum of all the area of its faces
For the two triangles
A = 2(0.5bh)
A = bh
A = 7 * 12 = 84 sq.ft
For the two rectangles
A = 2lw
A = 2(6*12)
A = 2 * 72 = 144 sq.ft
For the third triangle;
Area 6ft * 7ft
Area = 42 sq.feet
Taking the sum of the areas
TSA = 84 + 144 + 42
TSA = 270 sq ft
Hence the surface area of the right triangular prism is 270 sq ft
Learn more on surface area of prism here; brainly.com/question/1297098
Since beta is in the first quadrant, the final answer will be positive.
To find cos(beta) so we can use the half angle identity, we can substitute into the Pythagorean identity. Doing so gives us that

So, this means that

I'm pretty sure the answer is D bc it has the same coefficients and the same numbers