Determine a vector perpendicular to the plane

[joemama69]

Homework Statement

this problem has 2 parts

a- Determine a vector perpendicular to the plane containing the points 1,0,0 2,0,-1 1,4,3
b - determine the area of the triangle

Homework Equations

The Attempt at a Solution

a- i found the two vectors from the 1st point a = i - k, b = 4j + 3k
and i believe a X b would yield a perpindicular vector
a X b = 4i - 3j + 4k, is this correct


b - isn't the area of the triangle 1/2 the magnitude of the perpindicular vecor

.5(4^2 + 3^2 + 4^2)^1/2 = 3.201 is this correct

b - i don't really understand what the question is asking

c - center is (4,-1,-3)
r = (-1 + (8^2 + 2^2 + 6^2)/4)^1/2 = 5 is this correct

 

[dx]

Your answers to a and b are correct. What is the question for c?