The base of a triangular pyramid is a triangle with corners at (2 ,2 )(2,2), (3 ,1 )(3,1), and (7 ,5 )(7,5). If the pyramid has a height of 6 6, what is the pyramid's volume?

1 Answer
Mar 2, 2016

88

Explanation:

To find volume of a triangular pyramid of height 66 and base a triangle with corners at A(2,2)A(2,2), B(3,1)B(3,1), and C(7,5)C(7,5) we must find the area of the base triangle.

The sides of triangle can be found as follows.

AB=sqrt((3-2)^2+(1-2)^2)=sqrt2=1.4142AB=(32)2+(12)2=2=1.4142

BC=sqrt((7-3)^2+(5-1)^2)=sqrt(16+16)=sqrt32=5.6568BC=(73)2+(51)2=16+16=32=5.6568

CA=sqrt((7-2)^2+(5-2)^2)=sqrt(25+9)=sqrt34=5.831CA=(72)2+(52)2=25+9=34=5.831

Using Heron's formula s=(1.4142+5.6568+5.831)/2=6.451s=1.4142+5.6568+5.8312=6.451

and area of triangle is sqrt(6.451xx(6.451-1.4142)xx(6.451-5.6568)xx(6.451-5.831)6.451×(6.4511.4142)×(6.4515.6568)×(6.4515.831)
i.e. sqrt(6.451xx5.0368xx0.7942xx0.62)=46.451×5.0368×0.7942×0.62=4 (approx.)

As volume of pyramid 1/3xxheightxxarea of base13×height×areaofbase, it is 1/3xx4xx6=813×4×6=8