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=√(3−2)2+(1−2)2=√2=1.4142
BC=sqrt((7-3)^2+(5-1)^2)=sqrt(16+16)=sqrt32=5.6568BC=√(7−3)2+(5−1)2=√16+16=√32=5.6568
CA=sqrt((7-2)^2+(5-2)^2)=sqrt(25+9)=sqrt34=5.831CA=√(7−2)2+(5−2)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×(6.451−1.4142)×(6.451−5.6568)×(6.451−5.831)
i.e. sqrt(6.451xx5.0368xx0.7942xx0.62)=4√6.451×5.0368×0.7942×0.62=4 (approx.)
As volume of pyramid 1/3xxheightxxarea of base13×height×areaofbase, it is 1/3xx4xx6=813×4×6=8