Answer:
816 cm²
Step-by-step explanation:
Surface area of the composite figure = (surface area of the larger rectangular prism + surface area of the smaller rectangular prism) - area of the side of the smaller rectangular prism that is joined to the bigger prism.
✔️Surface area of the larger rectangular prism:
Area = L*W*H = 20*5*6 = 600 cm²
✔️surface area of the smaller rectangular prism:
Area = L*W*H = 12*4*6 = 288 cm²
✔️area of the side of the smaller rectangular prism that is joined to the bigger prism.
Area = L*W = 12*6 = 72 cm²
Surface area of the composite = (600 + 288) - 72 = 888 - 72 = 816 cm².
Label the 3 distinct sides of the box. I arbitrarily chose the letters a, b and c.
Use the info about areas as follows:
ab=54 in^2
ac=90 in^2
bc=60 in^2
Here you have 3 equations in 3 unknowns (a, b and c), which is enough info to use to determine a, b and c. Then the volume of the box is a*b*c.
Example: bc = 90, but c = 60/b. You could subst. 60/b for c in the 2nd and 3rd equation, which will eliminate c completely and leave you with 2 equations in 2 unknowns.
Continuing this procedure, I determined that a=9, b=6 and c=10. Thus, the volume of the box is V = 9*6*10 = 540 cubic inches (answer)
A, B and D are already rational numbers, 0.4 itself is a rational number, two rational numbers make a product of rational number.
So A, B, D are the correct choices.
Are you sure it asks for rational numbers, not irrational number?
R^2π=500in^2
r^2=500 in^2/π
r=(500 in^2/π)^(1/2)= 12.62 in
plug it in:
db=3da=3(2(12.62))= 75.69
r of b = 75.69/2=37.85in
A of b = (37.85in)^2π = 8.22 in^2
