Question

Question 3 Name the octants in which the following points lie:

(1, 2, 3), (4, –2, 3), (4, –2, –5), (4, 2, –5), (–4, 2, –5), (–4, 2, 5), (–3, –1, 6), (2, –4, –7)

Class X1 - Maths -Introduction to Three Dimensional Geometry Page 271

Answer 1

(1 , 2 , 3) : x - co-ordinate = +ve
y- co-ordinate = +ve
z- co-ordinate = +ve
hence, all the co-ordinates are positive so, name of octant is I

(4, - 2, 3) : x - co-ordinate = +ve
y - co-ordinate = -ve
z - co-ordinate = +ve
x and z co-ordinate are positive and y - co-ordinate is negative so, name of octant = IV

( 4, -2 , -5) : x - co-ordinate = +ve
y - co-ordinate = -ve
z - co-ordinate = -ve
so, name of octant = VIII

(4, 2, -5) : x - co-ordinate = +ve
y- co-ordinate = +ve
z- co-ordinate = -ve
so, name of octant = V

( -4, 2, -5) x - co-ordinate = -ve
y- co-ordinate = +ve
z - co-ordinate = -ve
so, name of octant = VI

(-4, 2, 5) x - co-ordinate = -ve
y- co-ordinate = +ve
z - co-ordinate = +ve
so, name of octant = II

(-3, -1, 6) x - co-ordinate = -ve
y- co-ordinate = -ve
z - co-ordinate = +ve
so, name of octant = III

(2, -4 , -7) x - co-ordinate = +ve
y- co-ordinate = -ve
z - co-ordinate = -ve
so, name of octant = VIII