Answer:
[tex]\large\boxed{4.\ V=\dfrac{33.64\pi x}{3}\approx35.21x}\\\boxed{5.\ V=21\ cm^3}[/tex]
Step-by-step explanation:
4.
The formula of a volume of a cone:
[tex]V=\dfrac{1}{3}\pi r^2H[/tex]
r - radius
H - height
We have
[tex]2r=11.6\to r=5.8,\ H=x[/tex]
Substitute:
[tex]V=\dfrac{1}{3}\pi(5.8^2)x=\dfrac{1}{3}\pi(33.64)x=\dfrac{33.64\pi x}{3}[/tex]
[tex]\pi\approx3.14[/tex]
[tex]V\approx\dfrac{(33.64)(3.14)x}{3}\approx35.21x[/tex]
5.
The formula of a volume of a pyramid:
[tex]V=\dfrac{1}{3}BH[/tex]
B - base area
H - height
In the base we have the square. The formula of an area of a square with side s:
[tex]A=s^2[/tex]
We have
[tex]s=3cm,\ H=7\ cm[/tex]
[tex]B=3^2=9\ cm^2[/tex]
[tex]V=\dfrac{1}{3}(9)(7)=(3)(7)=21\ cm^3[/tex]
