Find the lateral area the regular pyramid. Need help to solve it
would you say that's about right for the BOTTOM of the hexagonal pyramid?
5 times 6 times 6
180?
yes
ok, so, what would be "green" line? using the pythagorean theorem
5 so the answer is 180
would i set it up as 6^2 + 6^2 = x ?
well, $$ c^2= a^2+b^2\\ \text{what you need is "b",solve for "b"}\\ b^2 = c^2-a^2 \implies b = \sqrt{c^2-a^2} $$
from the right-angle, you have the hypotenuse, or "c", which the longest side, 6 the adjacent, or the shorter given side, or "a" which is 3
ok so b^2 = sqrt7 ?
yes
or \(\sqrt{27} = 3\sqrt{3}\)
so, now let's find the lateral sides "nose", or the so-called "slant-height"
keep in mind that, though slanted for perspective, the "yellow" triangle is a right-triangle so, using the known values, 8 and \(3\sqrt{3}\), use the pythagorean theorem to get the "longest" side, the one going to the top of the pyramid
the "longest" side will be the hypotenuse the opposite side, that is "b" is 8 the adjacent side, that is "a" is \(3\sqrt{3} $$ c^2= a^2+b^2\\ 3\sqrt{3} = \color{blue}{\sqrt{27}}\\ c^2 = (\color{blue}{\sqrt{27}})^2+(8)^2\\ c = \sqrt{(\color{blue}{\sqrt{27}})^2+(8)^2}\\ $$
hmmm
hehe my bad :)
the "longest" side will be the hypotenuse the opposite side, that is "b" is 8 the adjacent side, that is "a" is \(3\sqrt{3}\) $$ c^2= a^2+b^2\\ 3\sqrt{3} = \color{blue}{\sqrt{27}}\\ c^2 = (\color{blue}{\sqrt{27}})^2+(8)^2\\ c = \sqrt{(\color{blue}{\sqrt{27}})^2+(8)^2}\\ $$
c= 729 + 64 which = 793. So i then squareroot 793 ?
well, \((\sqrt{NUMBER})^2 = NUMBER\)
so \(c = \sqrt{(\color{blue}{\sqrt{27}})^2+(8)^2} = \sqrt{27+64} = \sqrt{91}\)
|dw:1371684071360:dw| so, now you just need to find the area of that triangle, that one face area of a triangle = \(\large \cfrac{1}{2} \times base \times height\) you get that area, the pyramid is a hexagon, so there are 6 of those triangles, add them together, and that's your Pyramid Lateral Area
180/2=90 which is final answer
base= 6 and height= sqrt 91 right?
yes
the area is sqrt 273?
$$ \cfrac{1}{2}\times 6 \times \sqrt{91} = 28.6\\ 28.6\times 6 = 171.6 $$
so i add all 6 and get 1,029.6
ahemm well, 1 triangle, that is 1 side, 1 lateral, is 28.6 in Area so 28.6 + 28.6 + 28.6 + 28.6 + 28.6 + 28.6 = 171.6
Oh. so the lateral area is 171.6?
yes, for a pyramid, the "laterals" or the "sides" area, that is, not including its bottom/base is the area of all her triangles around her
this one is a HEXAgon, so 6 sides, so 6 triangles, so you add them up
Thank you so much!!!
yw
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