45 POINTS FOR SOLVING THIS!!
Answer:
157.98 [tex]in^2[/tex]
Step-by-step explanation:
Given: volume of pyramid is equal to 100 cubic inches and height of the pyramid is 5 inches
To find: surface area of the pyramid
Solution:
Let h denotes the height of the pyramid and 'a' denotes side of the square base of the pyramid.
Volume of the pyramid = [tex]\frac{1}{3}a^2h[/tex]
Also,
Volume of the pyramid = 100 cubic inches
[tex]\frac{1}{3}a^2h=100\\\frac{1}{3}a^2(5)=100\\a^2=\frac{100\times 3}{5}=60\\a=\sqrt{60}[/tex]
Surface area of the pyramid [tex](S) =a\sqrt{4h^2+a^2}+a^2[/tex]
So,
[tex]S=\sqrt{60}\sqrt{100+60}+60\\=\sqrt{60}\sqrt{160}+60\\=\sqrt{9600}+60\\=97.9796+60\\=157.9796\\\approx 157.98[/tex]
Surface area = 157.98 [tex]in^2[/tex]
Answer:
Surface area of the pyramid = 157.99 in²
Step-by-step explanation:
Volume of a pyramid is given by the formula,
Volume = [tex]\frac{1}{3}(\text{Area of the base})\times \text{height}[/tex]
100 = [tex]\frac{1}{3}\text{(Side)}^{2} \times \text{height}[/tex]
300 = s² × 5
s² = 60
s = √60
s = 2√15 in ≈ 7.746 in
Now surface area of the pyramid = Area of base + 4×(Area of one lateral side)
Area of square base = (Side)² = 60 in
Area of one lateral side = [tex]\frac{1}{2}(\text{Base})(\text{Lateral height})[/tex]
Since Lateral height = [tex]\sqrt{(h)^{2}+(\frac{S}{2})^{2}}[/tex] [By applying Pythagoras theorem in the given triangle]
= [tex]\sqrt{(5)^{2}+(3.873)^{2}}[/tex]
= [tex]\sqrt{25+15}[/tex]
= [tex]\sqrt{40}[/tex]
= 6.325 in.
Now area of lateral side = [tex]\frac{1}{2}(7.746)(6.325)[/tex]
= 24.497 in²
Surface area of the pyramid = 60 + (4×24.497)
= 60 + 97.987
= 157.987 in²
≈ 157.99 in²