What is the area of a regular pentagon with a radius of 6 cm?
1 answer:
Answer:
85.6 cm^2
Step-by-step explanation:
The area of the central triangle bounded by each of the sides can be computed as ...
A = (1/2)r²sin(α) . . . . where α is the central angle, 360°/5 = 72°
There are 5 such triangles, so the area of the pentagon is ...
A = (5/2)(6 cm)²sin(72°) ≈ 85.595 cm²
The area of the regular pentagon of radius 6 cm is about 85.6 cm².
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Answer:
C. 14 metres cubed
Step-by-step explanation:
The volume of a sphere is denoted by: , where r is the radius, while the volume of a cylinder is denoted by:
, where r is the radius and h is the height.
Here, we know that the sphere and cylinder have the same radius and height. However, the "height" of the sphere is technically just the diameter, which is twice the radius. So, h = 2r. We know the volume of the cylinder is 21, so:
πr³ = 21/2 = 10.5
Now plug this into the volume of a sphere formula:
The answer is C, 14 metres cubed.