If the diameter of the smaller circle is 3.5cm, that means the radius is 1.75cm.
The area of the smaller circle is π × 1.75², which is ≈ 9.62112750162.
The diameter of the larger circle is 12.5 cm, so the radius would be half that, which is 6.25cm. The area of the larger circle would be π × 6.25², which is ≈ 122.718463031.
So now that we know the area of the larger circle and the smaller circle, we can find the area of the shaded region by subtracting the area of the smaller circle from the area of the larger circle, which is basically just 122.718463031 - 9.62112750162, which is = 113.097336. The closest answer here is 113.04, hence the answer is 113.04cm².
The pyramid given above has four faces. Each of which are in triangular shape. The area of the triangle is calculated through the equation,
A = bh / 2
where A is area, b is base and h is the height.
Substituting the known values,
A = (4 inch)(9 inch) / 2 = 18 in²
Multiplying this area by 4 will give us an answer of 72 in².
Then, we also calculate for the area of the square base.
A = s²
where s is the measure of each side of the square.
A = (4 in)² = 16 in²
Finally, we add up the calculated areas.
surface area = 72 in² + 16 in²
<em>surface area = 88 in²</em>
Hence, the surface area of the figure is equal to 88 in².
