Question
A pyramid with vertical height of 1ocm stands on a square base of sides 20cm .
a. Calculate to 3 significant figure for its total surface area.
b. If the pyramid is hollow what it's capacity in litres.
a. Calculate to 3 significant figure for its total surface area.
b. If the pyramid is hollow what it's capacity in litres.
Answers
Reiny
You don't say if in your surface ares you want to include the square base.
area of the 4 triangular sides:
need the height of one of them, 10^2 + 10^2= h^2
h = 10√2 cm
Area of one triangle = (1/2)(base)(height)
= (1/2)(20)10√2 = 100√2
add the area of the base which would be 400, if it should be included, you decide
vol = (1/3)(area of base)(height) <---- notice this height is the one given
= ....
area of the 4 triangular sides:
need the height of one of them, 10^2 + 10^2= h^2
h = 10√2 cm
Area of one triangle = (1/2)(base)(height)
= (1/2)(20)10√2 = 100√2
add the area of the base which would be 400, if it should be included, you decide
vol = (1/3)(area of base)(height) <---- notice this height is the one given
= ....
Dog_Lover
I'm not sure what "1o" centimeters means. But here's the formula for the surface area of a pyramid:
B + (1/2)(ps)
where B=area of the base, p=perimeter of the base and s=slant height. Use the Pythagorean Theorem to find the slant height.
For part b, you'll need the formula for the volume of a pyramid. Here it is:
(1/3)Bh
where B=area of the base and h=vertical height. That's all the information you need to solve this yourself.
B + (1/2)(ps)
where B=area of the base, p=perimeter of the base and s=slant height. Use the Pythagorean Theorem to find the slant height.
For part b, you'll need the formula for the volume of a pyramid. Here it is:
(1/3)Bh
where B=area of the base and h=vertical height. That's all the information you need to solve this yourself.