Chapter 11 - Vectors and Vector-Valued Functions - 11.2 Vectors in Three Dimensions - 11.2 Exercises - Page 778: 9

A: $(3,0,5)$ B: $(3,4,0)$ C: $(0,4,5)$

The vertex given is $(3,4,5)$, where $x=3$, $y=4$, and $z=5$. A is on the $xz$-plane, so the $y$ coordinate is zero. Thus, A is at $(3,0,5)$. B is on the $xy$-plane, so the $z$ coordinate is zero. Thus, B is at $(3,4,0)$. C is on the $yz$-plane, so the $x$ coordinate is zero. Thus, C is at $(0,4,5)$.