The base of a triangular pyramid is a triangle with corners at (1 ,2 )(1,2), (9 ,5 )(9,5), and (4 ,7 )(4,7). If the pyramid has a height of 9 9, what is the pyramid's volume?

2 Answers
Apr 1, 2018

Volume of a pyramid is 46.5 46.5 cubic.unit.

Explanation:

Volume of a pyramid is 1/3*13base area *hight.

(x_1,y_1)=(1 ,2) ,(x_2,y_2)=(9,5),(x_3,y_3)=(4,7) , h=9(x1,y1)=(1,2),(x2,y2)=(9,5),(x3,y3)=(4,7),h=9

Area of Triangle is A_b = |1/2(x1(y2−y3)+x2(y3−y1)+x3(y1−y2))|Ab=12(x1(y2y3)+x2(y3y1)+x3(y1y2))

A_b = |1/2(1(5−7)+9(7−2)+4(2−5))|Ab=12(1(57)+9(72)+4(25)) or

A_b = |1/2(-2+45-12)| = | 31/2| =31/2Ab=12(2+4512)=312=312sq.unit

Volume of a pyramid is 1/3*A_b*h = 1/3 *31/2*9 = 46.5 13Abh=133129=46.5

cubic.unit [Ans]

Apr 1, 2018

"volume "=93/2volume =932

Explanation:

"the volume (V) of a pyramid is calculated using"the volume (V) of a pyramid is calculated using
"the formula"the formula

•color(white)(x)V=1/3xx"area of base "xx"height"xV=13×area of base ×height

"the area of the base (A) is calculated using"the area of the base (A) is calculated using

•color(white)(x)A=1/2|x_1(y_2-y_3)+x_2(y_3-y_1)+x_3(y_1-y_2)|xA=12|x1(y2y3)+x2(y3y1)+x3(y1y2)|

"let "(x_1,y_1)=(1,2),(x_2,y_2)=(9,5),(x_3,y_3)=(4,7)let (x1,y1)=(1,2),(x2,y2)=(9,5),(x3,y3)=(4,7)

A=1/2|1(5-7)+9(7-2)+4(2-5)|A=12|1(57)+9(72)+4(25)|

color(white)(A)=1/2|-2+45-12|=31/2A=12|2+4512|=312

rArrV=1/3xx31/2xx9=93/2V=13×312×9=932